AIM: To define the magnetic resonance imaging(MRI) parameters differentiating urethral hypermobility(UH) and intrinsic sphincter deficiency(ISD) in women with stress urinary incontinence(SUI).METHODS: The static and d...AIM: To define the magnetic resonance imaging(MRI) parameters differentiating urethral hypermobility(UH) and intrinsic sphincter deficiency(ISD) in women with stress urinary incontinence(SUI).METHODS: The static and dynamic MR images of 21 patients with SUI were correlated to urodynamic(UD) findings and compared to those of 10 continent controls. For the assessment of the urethra and integrity of the urethral support structures, we applied the highresolution endocavitary MRI, such as intraurethral MRI, endovaginal or endorectal MRI. For the functional imaging of the urethral support, we performed dynamic MRI with the pelvic phased array coil. We assessed the following MRI parameters in both the patient and thevolunteer groups:(1) urethral angle;(2) bladder neck descent;(3) status of the periurethral ligaments,(4) vaginal shape;(5) urethral sphincter integrity, length and muscle thickness at mid urethra;(6) bladder neck funneling;(7) status of the puborectalis muscle;(8) pubo-vaginal distance. UDs parameters were assessed in the patient study group as follows:(1) urethral mobility angle on Q-tip test;(2) Valsalva leak point pressure(VLPP) measured at 250 cc bladder volume; and(3) maximum urethral closure pressure(MUCP). The UH type of SUI was defined with the Q-tip test angle over 30 degrees, and VLPP pressure over 60 cm H2 O. The ISD incontinence was defined with MUCP pressure below 20 cm H2 O, and VLPP pressure less or equal to 60 cm H2 O. We considered the associations between the MRI and clinical data and UDs using a variety of statistical tools to include linear regression, multivariate logistic regression and receiver operating characteristic(ROC) analysis. All statistical analyses were performed using STATA version 9.0(Stata Corp LP, College Station, TX).RESULTS: In the incontinent group, 52% have history of vaginal delivery trauma as compared to none in control group(P < 0.001). There was no difference between the continent volunteers and incontinent patients in body habitus as assessed by the body mass index. Pubovaginal distance and periurethral ligament disruption are significantly associated with incontinence; periurethral ligament symmetricity reduces the odds of incontinence by 87%. Bladder neck funneling and length of the suprapubic urethral sphincter are significantly associated with the type of incontinence on UDs; funneling reduced the odds of pure UH by almost 95%; increasing suprapubic urethral sphincter length at rest is highly associated with UH. Both MRI variables result in a predictive model for UDs diagnosis(area under the ROC = 0.944). CONCLUSION: MRI may play an important role in assessing the contribution of hypermobility and sphincteric dysfunction to the SUI in women when considering treatment options.展开更多
Small-bowel carcinoid tumors are the most common form(42%) of gastrointestinal carcinoids, which by themselves comprise 70% of neuroendocrine tumors. Although primary small bowel neoplasms are overall rare(3%-6% of al...Small-bowel carcinoid tumors are the most common form(42%) of gastrointestinal carcinoids, which by themselves comprise 70% of neuroendocrine tumors. Although primary small bowel neoplasms are overall rare(3%-6% of all gastrointestinal neoplasms), carcinoids still represent the second most common(20%-30%) primary small-bowel malignancy after small bowel adenocarcinoma. Their imaging evaluation is often challenging. State-of-the-art high-resolution multiphasic computed tomography together with advanced postprocessing methods provides an excellent tool for their depiction. The manifold interactive parameter choices however require knowledge of when to use which technique. Here, we discuss the imaging appearance and evaluation of duodenal, jejunal and ileal carcinoid tumors, including the imaging features of the primary tumor, locoregional mesenteric nodal metastases, and distant metastatic disease. A protocol for optimal lesion detection is presented, including the use of computed tomography enterography, volume acquisition, computed tomography angiography and three-dimensional mapping. Imaging findings are illustrated with a series of challenging cases which illustrate the spectrum of possible disease in the small bowel and mesentery, the range of possible appearances in the bowel itself on multiphase data and extraluminal findings such as the desmoplastic reaction in mesentery and hypervascular liver metastases. Typical imaging pitfalls and pearls are illustrated.展开更多
Over the past two decades,transcatheter arterial embolization has become the first-line therapy for the management of upper gastrointestinal bleeding that is refractory to endoscopic hemostasis.Advances in catheter-ba...Over the past two decades,transcatheter arterial embolization has become the first-line therapy for the management of upper gastrointestinal bleeding that is refractory to endoscopic hemostasis.Advances in catheter-based techniques and newer embolic agents, as well as recognition of the effectiveness of minimally invasive treatment options,have expanded the role of interventional radiology in the management of hemorrhage for a variety of indications,such as peptic ulcerbleeding,malignant disease,hemorrhagic Dieulafoy lesions and iatrogenic or trauma bleeding.Transcatheter interventions include the following:selective embolization of the feeding artery,sandwich coil occlusion of the gastroduodenal artery,blind or empiric embolization of the supposed bleeding vessel based on endoscopic findings and coil pseudoaneurysm or aneurysm embolization by three-dimensional sac packing with preservation of the parent artery.Transcatheter embolization is a fast,safe and effective,minimally invasive alternative to surgery when endoscopic treatment fails to control bleeding from the upper gastrointestinal tract.This article reviews the various transcatheter endovascular techniques and devices that are used in a variety of clinical scenarios for the management of hemorrhagic gastrointestinal emergencies.展开更多
AIM: To test the incremental value of 3T magnetic resonance neurography(MRN) in a series of unilateral radiculopathy patients with non-contributory magnetic resonance imaging(MRI).METHODS: Ten subjects(3 men,7 women; ...AIM: To test the incremental value of 3T magnetic resonance neurography(MRN) in a series of unilateral radiculopathy patients with non-contributory magnetic resonance imaging(MRI).METHODS: Ten subjects(3 men,7 women; mean age54 year and range 22-74 year) with unilateral lumbar radiculopathy and with previous non-contributory lumbar spine MRI underwent lumbosacral(LS) plexus MRN over a period of one year. Lumbar spine MRI performed as part of the MRN LS protocol as well as bilateral L4-S1 nerves,sciatic,femoral and lateral femoral cutaneous nerves were evaluated in each subject for neuropathy findings on both anatomic(nerve signal,course and caliber alterations) and diffusion tensor imaging(DTI)tensor maps(nerve signal and caliber alterations).Minimum fractional anisotropy(FA) and mean apparent diffusion coeffcient(ADC) of L4-S2 nerve roots,sciatic and femoral nerves were recorded.RESULTS: All anatomic studies and 80% of DTI imaging received a good-excellent imaging quality grading. In a blinded evaluation,all 10 examinations demonstrated neural and/or neuromuscular abnormality corresponding to the site of radiculopathy. A number of contributory neuropathy findings including double crush syndrome were observed. On DTI tensor maps,nerve signal and caliber alterations were more conspicuous. Although individual differences were observed among neuropathic appearing nerve(lower FA and increased ADC) as compared to its contralateral counterpart,there were no significant mean differences on statistical comparison of LS plexus nerves,femoral and sciatic nerves(P > 0.05).CONCLUSION: MRN of LS plexus is useful modality for the evaluation of patients with non-contributory MRI of lumbar spine as it can incrementally delineate the etiology and provide direct objective and non-invasive evidence of neuromuscular pathology.展开更多
AIM: To evaluate the pudendal nerve segments that could be identified on magnetic resonance neurography(MRN) before and after surgical marking of different nerve segments.METHODS: The hypothesis for this study was tha...AIM: To evaluate the pudendal nerve segments that could be identified on magnetic resonance neurography(MRN) before and after surgical marking of different nerve segments.METHODS: The hypothesis for this study was that pudendal nerve and its branches would be more easily seen after the surgical nerve marking. Institutional board approval was obtained. One male and one female cadaver pelvis were obtained from the anatomy board and were scanned using 3 Tesla MRI scanner using MR neurography sequences. All possible pudendal nerve branches were identified. The cadavers were then sent to the autopsy lab and were surgically dissected by a peripheral nerve surgeon and an anatomist to identify the pudendal nerve branches. Radiological markers were placed along the course of the pudendal nerve and its branches. The cadavers were then closed and rescanned using the same MRN protocol as the premarking scan. The remaining pudendal nerve branches were attempted to be identified using the radiological markers. All scans were read by an experienced musculoskeletal radiologist.RESULTS: The pre-marking MR Neurography scans clearly showed the pudendal nerve at its exit from the lumbosacral plexus in the sciatic notch, at the level of the ischial spine and in the Alcock's Canal in both cadavers. Additionally, the right hemorrhoidal branch could be identified in the male pelvis cadaver. The perineal and distal genital branches could not be identified. On post-marking scans, the markers were used as identifiable structures. The location of the perineal branch, the hemorroidal branch and the dorsal nerve to penis(in male cadaver)/clitoris(in female cadaver) could be seen. However, the visualization of these branches was suboptimal. The contralateral corresponding nerves were poorly seen despite marking on the surgical side. The nerve was best seen on axial T1W and T2W SPAIR images. The proximal segment could be seen well on 3D DW PSIF sequence. T2W SPACE was not very useful in visualization of this small nerve or its branches.CONCLUSION: Proximal pudendal nerve is easily seen on MR neurography, however it is not possible to identify distal branches of the pudendal nerve even after surgical marking.展开更多
Degenerative disc disease(DDD) is associated with intervertebral disc degeneration of spinal instability. Here, we report that the cilia of nucleus pulposus(NP) cells mediate mechanotransduction to maintain anabolic a...Degenerative disc disease(DDD) is associated with intervertebral disc degeneration of spinal instability. Here, we report that the cilia of nucleus pulposus(NP) cells mediate mechanotransduction to maintain anabolic activity in the discs. We found that mechanical stress promotes transport of parathyroid hormone 1 receptor(PTH1 R) to the cilia and enhances parathyroid hormone(PTH) signaling in NP cells. PTH induces transcription of integrin α_vβ_6 to activate the transforming growth factor(TGF)-β-connective tissue growth factor(CCN2)-matrix proteins signaling cascade. Intermittent injection of PTH(iPTH) effectively attenuates disc degeneration of aged mice by direct signaling through NP cells, specifically improving intervertebral disc height and volume by increasing levels of TGF-β activity, CCN2, and aggrecan. PTH1 R is expressed in both mouse and human NP cells. Importantly,knockout PTH1 R or cilia in the NP cells results in significant disc degeneration and blunts the effect of PTH on attenuation of aged discs. Thus, mechanical stress-induced transport of PTH1 R to the cilia enhances PTH signaling, which helps maintain intervertebral disc homeostasis, particularly during aging, indicating therapeutic potential of iPTH for DDD.展开更多
AIM:To evaluate two simple angle measurements for predicting lumbosacral transitional vertebra(LSTV) in magnetic resonance imaging(MRI) studies of the spine.METHODS:The lumbar spine MRI studies of 50 subjects with LST...AIM:To evaluate two simple angle measurements for predicting lumbosacral transitional vertebra(LSTV) in magnetic resonance imaging(MRI) studies of the spine.METHODS:The lumbar spine MRI studies of 50 subjects with LSTV and 50 subjects with normal lumbosacral anatomy were retrospectively evaluated.In each study,the mid-sagittal T2-weighted image was used to measure the angle formed by a line parallel to the superior surface of the sacrum and a line perpendicular to the axis of the scan table(A-angle),as well as the angle formed by a line parallel to the superior endplate of the L3 vertebra and a line parallel to the superior surface of the sacrum(B-angle).RESULTS:The total study population consisted of 100 subjects(46 males,54 females,51 ± 16 years old).There were no differences in age and sex between the two groups.Both A-angle and B-angle were significantly increased in subjects with LSTV compared to controls(P 【 0.05).The optimal cut-off values of A-angle and B-angle for the prediction of LSTV were 39.8°(sensitivity = 80%,specificity = 80%,accuracy = 83%;95% confidence interval = 74%-89%,P = 0.0001) and 35.9°(sensitivity = 80%,specificity = 54%,accuracy = 69%;95% confidence interval = 59%-78%,P = 0.0005),respectively.CONCLUSION:On sagittal MR images of the lumbar spine,an increased A-angle and/or B-angle should alert the radiologist to the presence of LSTV.展开更多
This article provides a review of Blood Oxygen Level Dependent functional magnetic resonance imaging(BOLD fMRI)applications for presurgical mapping in patients with brain tumors who are being considered for lesion res...This article provides a review of Blood Oxygen Level Dependent functional magnetic resonance imaging(BOLD fMRI)applications for presurgical mapping in patients with brain tumors who are being considered for lesion resection.Initially,the physical principle of the BOLD effect is discussed,followed by a general overview of the aims of presurgical planning.Subsequently,a review of sensorimotor,language and visual paradigms that are typically utilized in clinical fMRI is provided,followed by a brief description of studies demonstrating the clinical impact of preoperative BOLD fMRI.After this thorough introduction to presurgical fMRI,a detailed explanation of the phenomenon of neurovascular uncoupling(NVU),a major limitation of fMRI,is provided,followed by a discussion of the different approaches taken for BOLD cerebrovascular reactivity(CVR)mapping,which is an effective method of detecting NVU.We then include one clinical case which demonstrates the value of CVR mapping in clinical preoperative fMRI interpretation.The paper then concludes with a brief review of applications of CVR mapping other than for presurgical mapping.展开更多
Local cerebral metabolic rate of glucose(LCMRGlc) is an important index for the description of neural function.Dynamic 18 F-fluoro-2-deoxy-D-glucose(FDG) positron emission tomography(PET) has been used for quantitativ...Local cerebral metabolic rate of glucose(LCMRGlc) is an important index for the description of neural function.Dynamic 18 F-fluoro-2-deoxy-D-glucose(FDG) positron emission tomography(PET) has been used for quantitative imaging of LCMRGlc in humans,but is seldom used routinely because of the difficulty in obtaining the input function noninvasively.A reference tissue-based Patlak plot model(rPatlak) was proposed to generate parametric images of LCMRGlc in a quantitative dynamic FDG-PET study without requiring blood sampling.Dynamic emission scans(4×0.5,4×2 and 10×5 min) were acquired simultaneously with an IV bolus injection of 155 MBq of FDG.Arterial blood samples were collected during the scans via a catheter placed in the radial artery.Simulation data were also generated using the same scan sequence.The last ten scan data sets were used in a graphical analysis using the Patlak plot.The ratio of LCMRGlc estimated from the original Patlak(oPatlak,using plasma input) was used as the gold standard,and the standardized uptake value ratio(SUVR) was also calculated for comparison.Eight different tissues including white matter,gray matter,and whole brain were chosen as reference tissues for evaluation.Regardless of the reference region used,the slopes in the linear regression between oPatlak and rPatlak were closer to unity than the regression slopes between oPatlak and SUVR.The intercepts for the former were also closer to 0 than those for the latter case.The squared correlation coefficients were close to 1.0 for both cases.This showed that the results of rPatlak were in good agreement with those of oPatlak,however,SUVR exhibited more deviation.The simulation study also showed that the relative variance and bias for rPatlak were less than those for SUVR.The images obtained with rPatlak were very similar to those obtained with oPatlak,while there were differences in the relative spatial distribution between the images of SUVR and oPatlak.This study validates that the rPatlak method is better than the SUVR method and is a good approximation to the oPatlak method.The new method is suitable for generating LCMRGlc parametric images noninvasively.展开更多
The purpose of the present study was to assess the reproducibility of voxel placement for GABA-edited MRS. GABA-edited MRS data were acquired in 13 healthy volunteers from (3 cm)3 voxel;and within the same session a s...The purpose of the present study was to assess the reproducibility of voxel placement for GABA-edited MRS. GABA-edited MRS data were acquired in 13 healthy volunteers from (3 cm)3 voxel;and within the same session a second acquisition was independently prescribed. A three-dimensional voxel mask image was reconstructed in T1-image-space using the SVMask tool (in house software). Reproducibility of voxel placement was assessed using the Dice overlap coefficient, both within-subject and between-subject following co-registration of T1 images and transformation of voxel mask images to standard space. Within-subject overlap coefficients were 86% ± 5%. Between-subject overlap coefficients were 75% ± 10%. For the two voxel locations considered (occipital and sensorimotor), voxel overlap was very similar. Between-subject values are higher due to between-session effects, anatomical variability and volume mismatch in standard space. While surprisingly low in terms of volume overlap, the overlap coefficients correspond to acceptable linear displacements.展开更多
One of the most common cancers worldwide, colorectal cancer (CRC) has been associated with significant morbidity and mortality and therefore represents an enormous burden to the health care system. Recent advances in ...One of the most common cancers worldwide, colorectal cancer (CRC) has been associated with significant morbidity and mortality and therefore represents an enormous burden to the health care system. Recent advances in CRC treatments have provided patients with primary and metastatic CRC a better long-term prognosis. The presence of synchronous or metachronous metastasis has been associated, however, with worse survival. The most common site of metastatic disease is the liver. A variety of treatment modalities aimed at targeting colorectal liver metastases (CRLM) has been demonstrated to improve the prognosis of these patients. Loco-regional approaches such as surgical resection and tumor ablation (operative and percutaneous) can provide patients with a chance at long-term disease control and even cure in select populations. Patient selection is important in defining the most suitable treatment option for CRLM in order to provide the best possible survival benefit while avoiding unnecessary interventions and adverse events. Medical imaging plays a crucial role in evaluating the characteristics of CRLMs and disease resectability. Size of tumors, proximity to adjacent anatomical structures, and volume of the unaffected liver are among the most important imaging parameters to determine the suitability of patients for surgical management or other appropriate treatment approaches. We herein provide a comprehensive overview of current-state-of-the-art imaging in the management of CRLM, including staging, treatment planning, response and survival assessment, and post-treatment surveillance. Computed tomography (CT) scan and magnetic resonance imaging (MRI) are two most commonly used techniques, which can be used solely or in combination with functional imaging modalities such as positron emission tomography (PET) and diffusion weighted imaging (DWI). Providing up-to-date evidence on advantages and disadvantages of imaging modalities and tumor assessment criteria, the current review offers a practice guide to assist providers in choosing the most suitable imaging approach for patients with CRLM.展开更多
Glioblastoma(GBM,WHO grade IV glioma)is the most common and lethal malignant brain tumor in aduts with a dismal prognosis.The extracellular matrix(ECM)supports GBM progression by promoting tumor cell proliferation,mig...Glioblastoma(GBM,WHO grade IV glioma)is the most common and lethal malignant brain tumor in aduts with a dismal prognosis.The extracellular matrix(ECM)supports GBM progression by promoting tumor cell proliferation,migration,and immune escape.Uridine diphosphate(UDP)-glucose 6-dehydrogenase(UGDH)is the rate-limiting enzyme that catalyzes the biosynthesis of glycosaminoglycans that are the principal component of the CNS ECM.We investigated how targeting UGDH in GBM infuence$the GBM immune microenvironment,including tumor-associated microglia/macrophages(TAMs)and T cells.TAMs are the main im-mune effector cells in GBM and can directly target tumor cells if properly activated.In co-cultures of GBM cells and human primary macrophages,UGDH knockdown in GBM cells pro-moted macrophage phagocytosis and M-like polarization.In orthotropic human GBM xeno-grafts and syngeneic mouse glioma models,targeting UGDH decreased ECM deposition,increased TAM phagocytosis marker expression,reduced M2-like TAMS and inhibited tumor growth.UGDH knockdown in GBM cells also promoted cytotoxic T cell ifltration and activa-tion in orthotopic syngeneic mouse glioma models.The potent and in-human-use small mole-cule GAG synthesis inhibitor 4-methylumbelliferone(4-MU)was found to inhibit GBM cell proliferation and migration in vitro,mimic the macrophage and T-cell responses to UGDH knockdown in vitro and in vivo and inhibit growth of orthotopic murine GBM.Our study shows that UGDH supports GBM growth through multiple mechanisms and supports the development of ECM-based therapeutic strategies to simultaneously target tumor cells and their microenvi-ronment.展开更多
Background and Aims:To investigate the impact of MR bias field correction on response determination and survival prediction using volumetric tumor enhancement analysis in patients with infiltrative hepatocellular carc...Background and Aims:To investigate the impact of MR bias field correction on response determination and survival prediction using volumetric tumor enhancement analysis in patients with infiltrative hepatocellular carcinoma,after transcatheter arterial chemoembolization(TACE).Methods:This study included 101 patients treated with conventional or drug-eluting beads TACE between the years of 2001 and 2013.Semi-automated 3D quantification software was used to segment and calculate the enhancing tumor volume(ETV)of the liver with and without bias-field correction on multi-phasic contrast-enhanced MRI before and 1-month after initial TACE.ETV(expressed as cm3)at baseline imaging and the relative change in ETV(as%change,ETV%)before and after TACE were used to predict response and survival,respectively.Statistical survival analyses included Kaplan-Meier curve generation and Cox proportional hazards modeling.Q statistics were calculated and used to identify the best cut-off value for ETV to separate responders and non-responders(ETV cm3).The difference in survival was evaluated between responders and non-responders using Kaplan-Meier and Cox models.Results:MR bias field correction correlated with improved response calculation from baseline MR as well as survival after TACE;using a 415 cm3 cut-off for ETV at baseline(hazard ratio:2.00,95%confidence interval:1.23-3.26,p=0.01)resulted in significantly improved response prediction(median survival in patients with baseline ETV<415 cm3:19.66 months vs.≥415 cm3:9.21 months,p<0.001,log-rank test).A≥41%relative decrease in ETV(hazard ratio:0.58,95%confidence interval:0.37-0.93,p=0.02)was significant in predicting survival(ETV≥41%:19.20 months vs.ETV<41%:8.71 months,p=0.008,log-rank test).Without MR bias field correction,response from baseline ETV could be predicted but survival after TACE could not.Conclusions:MR bias field correction improves both response assessment and accuracy of survival prediction using whole liver tumor enhancement analysis from baseline MR after initial TACE in patients with infiltrative hepatocellular carcinoma.展开更多
基金Supported by The Radiological Society of North America and the Society of Computed Body Tomography and Magnetic Resonance
文摘AIM: To define the magnetic resonance imaging(MRI) parameters differentiating urethral hypermobility(UH) and intrinsic sphincter deficiency(ISD) in women with stress urinary incontinence(SUI).METHODS: The static and dynamic MR images of 21 patients with SUI were correlated to urodynamic(UD) findings and compared to those of 10 continent controls. For the assessment of the urethra and integrity of the urethral support structures, we applied the highresolution endocavitary MRI, such as intraurethral MRI, endovaginal or endorectal MRI. For the functional imaging of the urethral support, we performed dynamic MRI with the pelvic phased array coil. We assessed the following MRI parameters in both the patient and thevolunteer groups:(1) urethral angle;(2) bladder neck descent;(3) status of the periurethral ligaments,(4) vaginal shape;(5) urethral sphincter integrity, length and muscle thickness at mid urethra;(6) bladder neck funneling;(7) status of the puborectalis muscle;(8) pubo-vaginal distance. UDs parameters were assessed in the patient study group as follows:(1) urethral mobility angle on Q-tip test;(2) Valsalva leak point pressure(VLPP) measured at 250 cc bladder volume; and(3) maximum urethral closure pressure(MUCP). The UH type of SUI was defined with the Q-tip test angle over 30 degrees, and VLPP pressure over 60 cm H2 O. The ISD incontinence was defined with MUCP pressure below 20 cm H2 O, and VLPP pressure less or equal to 60 cm H2 O. We considered the associations between the MRI and clinical data and UDs using a variety of statistical tools to include linear regression, multivariate logistic regression and receiver operating characteristic(ROC) analysis. All statistical analyses were performed using STATA version 9.0(Stata Corp LP, College Station, TX).RESULTS: In the incontinent group, 52% have history of vaginal delivery trauma as compared to none in control group(P < 0.001). There was no difference between the continent volunteers and incontinent patients in body habitus as assessed by the body mass index. Pubovaginal distance and periurethral ligament disruption are significantly associated with incontinence; periurethral ligament symmetricity reduces the odds of incontinence by 87%. Bladder neck funneling and length of the suprapubic urethral sphincter are significantly associated with the type of incontinence on UDs; funneling reduced the odds of pure UH by almost 95%; increasing suprapubic urethral sphincter length at rest is highly associated with UH. Both MRI variables result in a predictive model for UDs diagnosis(area under the ROC = 0.944). CONCLUSION: MRI may play an important role in assessing the contribution of hypermobility and sphincteric dysfunction to the SUI in women when considering treatment options.
文摘Small-bowel carcinoid tumors are the most common form(42%) of gastrointestinal carcinoids, which by themselves comprise 70% of neuroendocrine tumors. Although primary small bowel neoplasms are overall rare(3%-6% of all gastrointestinal neoplasms), carcinoids still represent the second most common(20%-30%) primary small-bowel malignancy after small bowel adenocarcinoma. Their imaging evaluation is often challenging. State-of-the-art high-resolution multiphasic computed tomography together with advanced postprocessing methods provides an excellent tool for their depiction. The manifold interactive parameter choices however require knowledge of when to use which technique. Here, we discuss the imaging appearance and evaluation of duodenal, jejunal and ileal carcinoid tumors, including the imaging features of the primary tumor, locoregional mesenteric nodal metastases, and distant metastatic disease. A protocol for optimal lesion detection is presented, including the use of computed tomography enterography, volume acquisition, computed tomography angiography and three-dimensional mapping. Imaging findings are illustrated with a series of challenging cases which illustrate the spectrum of possible disease in the small bowel and mesentery, the range of possible appearances in the bowel itself on multiphase data and extraluminal findings such as the desmoplastic reaction in mesentery and hypervascular liver metastases. Typical imaging pitfalls and pearls are illustrated.
文摘Over the past two decades,transcatheter arterial embolization has become the first-line therapy for the management of upper gastrointestinal bleeding that is refractory to endoscopic hemostasis.Advances in catheter-based techniques and newer embolic agents, as well as recognition of the effectiveness of minimally invasive treatment options,have expanded the role of interventional radiology in the management of hemorrhage for a variety of indications,such as peptic ulcerbleeding,malignant disease,hemorrhagic Dieulafoy lesions and iatrogenic or trauma bleeding.Transcatheter interventions include the following:selective embolization of the feeding artery,sandwich coil occlusion of the gastroduodenal artery,blind or empiric embolization of the supposed bleeding vessel based on endoscopic findings and coil pseudoaneurysm or aneurysm embolization by three-dimensional sac packing with preservation of the parent artery.Transcatheter embolization is a fast,safe and effective,minimally invasive alternative to surgery when endoscopic treatment fails to control bleeding from the upper gastrointestinal tract.This article reviews the various transcatheter endovascular techniques and devices that are used in a variety of clinical scenarios for the management of hemorrhagic gastrointestinal emergencies.
文摘AIM: To test the incremental value of 3T magnetic resonance neurography(MRN) in a series of unilateral radiculopathy patients with non-contributory magnetic resonance imaging(MRI).METHODS: Ten subjects(3 men,7 women; mean age54 year and range 22-74 year) with unilateral lumbar radiculopathy and with previous non-contributory lumbar spine MRI underwent lumbosacral(LS) plexus MRN over a period of one year. Lumbar spine MRI performed as part of the MRN LS protocol as well as bilateral L4-S1 nerves,sciatic,femoral and lateral femoral cutaneous nerves were evaluated in each subject for neuropathy findings on both anatomic(nerve signal,course and caliber alterations) and diffusion tensor imaging(DTI)tensor maps(nerve signal and caliber alterations).Minimum fractional anisotropy(FA) and mean apparent diffusion coeffcient(ADC) of L4-S2 nerve roots,sciatic and femoral nerves were recorded.RESULTS: All anatomic studies and 80% of DTI imaging received a good-excellent imaging quality grading. In a blinded evaluation,all 10 examinations demonstrated neural and/or neuromuscular abnormality corresponding to the site of radiculopathy. A number of contributory neuropathy findings including double crush syndrome were observed. On DTI tensor maps,nerve signal and caliber alterations were more conspicuous. Although individual differences were observed among neuropathic appearing nerve(lower FA and increased ADC) as compared to its contralateral counterpart,there were no significant mean differences on statistical comparison of LS plexus nerves,femoral and sciatic nerves(P > 0.05).CONCLUSION: MRN of LS plexus is useful modality for the evaluation of patients with non-contributory MRI of lumbar spine as it can incrementally delineate the etiology and provide direct objective and non-invasive evidence of neuromuscular pathology.
文摘AIM: To evaluate the pudendal nerve segments that could be identified on magnetic resonance neurography(MRN) before and after surgical marking of different nerve segments.METHODS: The hypothesis for this study was that pudendal nerve and its branches would be more easily seen after the surgical nerve marking. Institutional board approval was obtained. One male and one female cadaver pelvis were obtained from the anatomy board and were scanned using 3 Tesla MRI scanner using MR neurography sequences. All possible pudendal nerve branches were identified. The cadavers were then sent to the autopsy lab and were surgically dissected by a peripheral nerve surgeon and an anatomist to identify the pudendal nerve branches. Radiological markers were placed along the course of the pudendal nerve and its branches. The cadavers were then closed and rescanned using the same MRN protocol as the premarking scan. The remaining pudendal nerve branches were attempted to be identified using the radiological markers. All scans were read by an experienced musculoskeletal radiologist.RESULTS: The pre-marking MR Neurography scans clearly showed the pudendal nerve at its exit from the lumbosacral plexus in the sciatic notch, at the level of the ischial spine and in the Alcock's Canal in both cadavers. Additionally, the right hemorrhoidal branch could be identified in the male pelvis cadaver. The perineal and distal genital branches could not be identified. On post-marking scans, the markers were used as identifiable structures. The location of the perineal branch, the hemorroidal branch and the dorsal nerve to penis(in male cadaver)/clitoris(in female cadaver) could be seen. However, the visualization of these branches was suboptimal. The contralateral corresponding nerves were poorly seen despite marking on the surgical side. The nerve was best seen on axial T1W and T2W SPAIR images. The proximal segment could be seen well on 3D DW PSIF sequence. T2W SPACE was not very useful in visualization of this small nerve or its branches.CONCLUSION: Proximal pudendal nerve is easily seen on MR neurography, however it is not possible to identify distal branches of the pudendal nerve even after surgical marking.
基金supported by the National Institute of Arthritis and Musculoskeletal and Skin Diseases of the National Institutes of Health under Award Numbers AR071432 and AR063943
文摘Degenerative disc disease(DDD) is associated with intervertebral disc degeneration of spinal instability. Here, we report that the cilia of nucleus pulposus(NP) cells mediate mechanotransduction to maintain anabolic activity in the discs. We found that mechanical stress promotes transport of parathyroid hormone 1 receptor(PTH1 R) to the cilia and enhances parathyroid hormone(PTH) signaling in NP cells. PTH induces transcription of integrin α_vβ_6 to activate the transforming growth factor(TGF)-β-connective tissue growth factor(CCN2)-matrix proteins signaling cascade. Intermittent injection of PTH(iPTH) effectively attenuates disc degeneration of aged mice by direct signaling through NP cells, specifically improving intervertebral disc height and volume by increasing levels of TGF-β activity, CCN2, and aggrecan. PTH1 R is expressed in both mouse and human NP cells. Importantly,knockout PTH1 R or cilia in the NP cells results in significant disc degeneration and blunts the effect of PTH on attenuation of aged discs. Thus, mechanical stress-induced transport of PTH1 R to the cilia enhances PTH signaling, which helps maintain intervertebral disc homeostasis, particularly during aging, indicating therapeutic potential of iPTH for DDD.
文摘AIM:To evaluate two simple angle measurements for predicting lumbosacral transitional vertebra(LSTV) in magnetic resonance imaging(MRI) studies of the spine.METHODS:The lumbar spine MRI studies of 50 subjects with LSTV and 50 subjects with normal lumbosacral anatomy were retrospectively evaluated.In each study,the mid-sagittal T2-weighted image was used to measure the angle formed by a line parallel to the superior surface of the sacrum and a line perpendicular to the axis of the scan table(A-angle),as well as the angle formed by a line parallel to the superior endplate of the L3 vertebra and a line parallel to the superior surface of the sacrum(B-angle).RESULTS:The total study population consisted of 100 subjects(46 males,54 females,51 ± 16 years old).There were no differences in age and sex between the two groups.Both A-angle and B-angle were significantly increased in subjects with LSTV compared to controls(P 【 0.05).The optimal cut-off values of A-angle and B-angle for the prediction of LSTV were 39.8°(sensitivity = 80%,specificity = 80%,accuracy = 83%;95% confidence interval = 74%-89%,P = 0.0001) and 35.9°(sensitivity = 80%,specificity = 54%,accuracy = 69%;95% confidence interval = 59%-78%,P = 0.0005),respectively.CONCLUSION:On sagittal MR images of the lumbar spine,an increased A-angle and/or B-angle should alert the radiologist to the presence of LSTV.
文摘This article provides a review of Blood Oxygen Level Dependent functional magnetic resonance imaging(BOLD fMRI)applications for presurgical mapping in patients with brain tumors who are being considered for lesion resection.Initially,the physical principle of the BOLD effect is discussed,followed by a general overview of the aims of presurgical planning.Subsequently,a review of sensorimotor,language and visual paradigms that are typically utilized in clinical fMRI is provided,followed by a brief description of studies demonstrating the clinical impact of preoperative BOLD fMRI.After this thorough introduction to presurgical fMRI,a detailed explanation of the phenomenon of neurovascular uncoupling(NVU),a major limitation of fMRI,is provided,followed by a discussion of the different approaches taken for BOLD cerebrovascular reactivity(CVR)mapping,which is an effective method of detecting NVU.We then include one clinical case which demonstrates the value of CVR mapping in clinical preoperative fMRI interpretation.The paper then concludes with a brief review of applications of CVR mapping other than for presurgical mapping.
基金supported by the National Natural Science Foundation of China (30840033,30770615 and 30970818)the National Basic Research Program of China (2011CB707701)the Joint Research Foundation of Beijing Education Committee (JD100010607)
文摘Local cerebral metabolic rate of glucose(LCMRGlc) is an important index for the description of neural function.Dynamic 18 F-fluoro-2-deoxy-D-glucose(FDG) positron emission tomography(PET) has been used for quantitative imaging of LCMRGlc in humans,but is seldom used routinely because of the difficulty in obtaining the input function noninvasively.A reference tissue-based Patlak plot model(rPatlak) was proposed to generate parametric images of LCMRGlc in a quantitative dynamic FDG-PET study without requiring blood sampling.Dynamic emission scans(4×0.5,4×2 and 10×5 min) were acquired simultaneously with an IV bolus injection of 155 MBq of FDG.Arterial blood samples were collected during the scans via a catheter placed in the radial artery.Simulation data were also generated using the same scan sequence.The last ten scan data sets were used in a graphical analysis using the Patlak plot.The ratio of LCMRGlc estimated from the original Patlak(oPatlak,using plasma input) was used as the gold standard,and the standardized uptake value ratio(SUVR) was also calculated for comparison.Eight different tissues including white matter,gray matter,and whole brain were chosen as reference tissues for evaluation.Regardless of the reference region used,the slopes in the linear regression between oPatlak and rPatlak were closer to unity than the regression slopes between oPatlak and SUVR.The intercepts for the former were also closer to 0 than those for the latter case.The squared correlation coefficients were close to 1.0 for both cases.This showed that the results of rPatlak were in good agreement with those of oPatlak,however,SUVR exhibited more deviation.The simulation study also showed that the relative variance and bias for rPatlak were less than those for SUVR.The images obtained with rPatlak were very similar to those obtained with oPatlak,while there were differences in the relative spatial distribution between the images of SUVR and oPatlak.This study validates that the rPatlak method is better than the SUVR method and is a good approximation to the oPatlak method.The new method is suitable for generating LCMRGlc parametric images noninvasively.
基金supported by NIH grants R01 EB016089 and P41 EB015909
文摘The purpose of the present study was to assess the reproducibility of voxel placement for GABA-edited MRS. GABA-edited MRS data were acquired in 13 healthy volunteers from (3 cm)3 voxel;and within the same session a second acquisition was independently prescribed. A three-dimensional voxel mask image was reconstructed in T1-image-space using the SVMask tool (in house software). Reproducibility of voxel placement was assessed using the Dice overlap coefficient, both within-subject and between-subject following co-registration of T1 images and transformation of voxel mask images to standard space. Within-subject overlap coefficients were 86% ± 5%. Between-subject overlap coefficients were 75% ± 10%. For the two voxel locations considered (occipital and sensorimotor), voxel overlap was very similar. Between-subject values are higher due to between-session effects, anatomical variability and volume mismatch in standard space. While surprisingly low in terms of volume overlap, the overlap coefficients correspond to acceptable linear displacements.
文摘One of the most common cancers worldwide, colorectal cancer (CRC) has been associated with significant morbidity and mortality and therefore represents an enormous burden to the health care system. Recent advances in CRC treatments have provided patients with primary and metastatic CRC a better long-term prognosis. The presence of synchronous or metachronous metastasis has been associated, however, with worse survival. The most common site of metastatic disease is the liver. A variety of treatment modalities aimed at targeting colorectal liver metastases (CRLM) has been demonstrated to improve the prognosis of these patients. Loco-regional approaches such as surgical resection and tumor ablation (operative and percutaneous) can provide patients with a chance at long-term disease control and even cure in select populations. Patient selection is important in defining the most suitable treatment option for CRLM in order to provide the best possible survival benefit while avoiding unnecessary interventions and adverse events. Medical imaging plays a crucial role in evaluating the characteristics of CRLMs and disease resectability. Size of tumors, proximity to adjacent anatomical structures, and volume of the unaffected liver are among the most important imaging parameters to determine the suitability of patients for surgical management or other appropriate treatment approaches. We herein provide a comprehensive overview of current-state-of-the-art imaging in the management of CRLM, including staging, treatment planning, response and survival assessment, and post-treatment surveillance. Computed tomography (CT) scan and magnetic resonance imaging (MRI) are two most commonly used techniques, which can be used solely or in combination with functional imaging modalities such as positron emission tomography (PET) and diffusion weighted imaging (DWI). Providing up-to-date evidence on advantages and disadvantages of imaging modalities and tumor assessment criteria, the current review offers a practice guide to assist providers in choosing the most suitable imaging approach for patients with CRLM.
基金This work was supported by grants from NIH R01NS091165(S.X.),R01 NS099460(M Ying),R01 NS096754(J Laterra),and R01 NS076759(J Laterra)。
文摘Glioblastoma(GBM,WHO grade IV glioma)is the most common and lethal malignant brain tumor in aduts with a dismal prognosis.The extracellular matrix(ECM)supports GBM progression by promoting tumor cell proliferation,migration,and immune escape.Uridine diphosphate(UDP)-glucose 6-dehydrogenase(UGDH)is the rate-limiting enzyme that catalyzes the biosynthesis of glycosaminoglycans that are the principal component of the CNS ECM.We investigated how targeting UGDH in GBM infuence$the GBM immune microenvironment,including tumor-associated microglia/macrophages(TAMs)and T cells.TAMs are the main im-mune effector cells in GBM and can directly target tumor cells if properly activated.In co-cultures of GBM cells and human primary macrophages,UGDH knockdown in GBM cells pro-moted macrophage phagocytosis and M-like polarization.In orthotropic human GBM xeno-grafts and syngeneic mouse glioma models,targeting UGDH decreased ECM deposition,increased TAM phagocytosis marker expression,reduced M2-like TAMS and inhibited tumor growth.UGDH knockdown in GBM cells also promoted cytotoxic T cell ifltration and activa-tion in orthotopic syngeneic mouse glioma models.The potent and in-human-use small mole-cule GAG synthesis inhibitor 4-methylumbelliferone(4-MU)was found to inhibit GBM cell proliferation and migration in vitro,mimic the macrophage and T-cell responses to UGDH knockdown in vitro and in vivo and inhibit growth of orthotopic murine GBM.Our study shows that UGDH supports GBM growth through multiple mechanisms and supports the development of ECM-based therapeutic strategies to simultaneously target tumor cells and their microenvi-ronment.
文摘Background and Aims:To investigate the impact of MR bias field correction on response determination and survival prediction using volumetric tumor enhancement analysis in patients with infiltrative hepatocellular carcinoma,after transcatheter arterial chemoembolization(TACE).Methods:This study included 101 patients treated with conventional or drug-eluting beads TACE between the years of 2001 and 2013.Semi-automated 3D quantification software was used to segment and calculate the enhancing tumor volume(ETV)of the liver with and without bias-field correction on multi-phasic contrast-enhanced MRI before and 1-month after initial TACE.ETV(expressed as cm3)at baseline imaging and the relative change in ETV(as%change,ETV%)before and after TACE were used to predict response and survival,respectively.Statistical survival analyses included Kaplan-Meier curve generation and Cox proportional hazards modeling.Q statistics were calculated and used to identify the best cut-off value for ETV to separate responders and non-responders(ETV cm3).The difference in survival was evaluated between responders and non-responders using Kaplan-Meier and Cox models.Results:MR bias field correction correlated with improved response calculation from baseline MR as well as survival after TACE;using a 415 cm3 cut-off for ETV at baseline(hazard ratio:2.00,95%confidence interval:1.23-3.26,p=0.01)resulted in significantly improved response prediction(median survival in patients with baseline ETV<415 cm3:19.66 months vs.≥415 cm3:9.21 months,p<0.001,log-rank test).A≥41%relative decrease in ETV(hazard ratio:0.58,95%confidence interval:0.37-0.93,p=0.02)was significant in predicting survival(ETV≥41%:19.20 months vs.ETV<41%:8.71 months,p=0.008,log-rank test).Without MR bias field correction,response from baseline ETV could be predicted but survival after TACE could not.Conclusions:MR bias field correction improves both response assessment and accuracy of survival prediction using whole liver tumor enhancement analysis from baseline MR after initial TACE in patients with infiltrative hepatocellular carcinoma.