With the widespread of cross-sectional imaging, a growth of incidentally detected focal liver lesions(FLL) has been observed. A reliable detection and characterization of FLL is critical for optimal patient management...With the widespread of cross-sectional imaging, a growth of incidentally detected focal liver lesions(FLL) has been observed. A reliable detection and characterization of FLL is critical for optimal patient management. Maximizing accuracy of imaging in the context of FLL is paramount in avoiding unnecessary biopsies, which may result in post-procedural complications. A tremendous development of new imaging techniques has taken place during these last years. Nowadays, Magnetic resonance imaging(MRI) plays a key role in management of liver lesions, using a radiation-free technique and a safe contrast agent profile. MRI plays a key role in the non-invasive correct characterization of FLL. MRI is capable of providing comprehensive and highly accurate diagnostic information, with the additional advantage of lack of harmful ionizing radiation. These properties make MRI the mainstay for the noninvasive evaluation of focal liver lesions. In this paper we review the state-of-the-art MRI liver protocol, briefly discussing different sequence types, the unique characteristics of imaging non-cooperative patients and discuss the role of hepatocyte-specific contrast agents. A review of the imaging features of the most common benign and malignant FLL is presented, supplemented by a schematic representation of a simplistic practical approach on MRI.展开更多
Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential...Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential element in cardiovascular and abdominal imaging.In addition to sonography and computer tomography,MRI is a valuable tool for diagnosing cardiovascular and abdominal diseases,for determining disease severity,and for assessing therapeutic success.MRI techniques have improved over the last few decades,revealing not just morphologic information,but functional information about perfusion,diffusion and hemodynamics as well.Four-dimensional(4D)flow MRI,a time-resolved phase contrast-MRI with three-dimensional(3D)anatomic coverage and velocity encoding along all three flow directions has been used to comprehensively assess complex cardiovascular hemodynamics in multiple regions of the body.The technique enables visualization of 3D blood flow patterns and retrospective quantification of blood flow parameters in a region of interest.Over the last few years,4D flow MRI has been increasingly performed in the abdominal region.By applying different acceleration techniques,taking 4D flow MRI measurements has dropped to a reasonable scanning time of 8 to 12 min.These new developments have encouraged a growing number of patient studies in the literature validating the technique’s potential for enhanced evaluation of blood flow parameters within the liver’s complex vascular system.The purpose of this review article is to broaden our understanding of 4D flow MRI for the assessment of liver hemodynamics by providing insights into acquisition,data analysis,visualization and quantification.Furthermore,in this article we highlight its development,focussing on the clinical application of the technique.展开更多
AIM: To establish a prognostic formula that distinguishes non-hypervascular hepatic nodules(NHNs) with higher aggressiveness from less hazardous one. METHODS: Seventy-three NHNs were detected in gadolinium ethoxybenzy...AIM: To establish a prognostic formula that distinguishes non-hypervascular hepatic nodules(NHNs) with higher aggressiveness from less hazardous one. METHODS: Seventy-three NHNs were detected in gadolinium ethoxybenzyl diethylene-triamine-pentaaceticacid magnetic resonance imaging(Gd-EOB-DTPA-MRI) study and confirmed to change 2 mm or more in size and/or to gain hypervascularity. All images were interpreted independently by an experienced, board-certified abdominal radiologist and hepatologist; both knew thatthe patients were at risk for hepatocellular carcinoma development but were blinded to the clinical information. A formula predicting NHN destiny was developed using a generalized estimating equation model with thirteen explanatory variables: age, gender, background liver diseases, Child-Pugh class, NHN diameter, T1-weighted imaging/T2-weighted imaging detectability, fat deposition, lower signal intensity in arterial phase, lower signal intensity in equilibrium phase, α-fetoprotein, des-γ-carboxy prothrombin, α-fetoprotein-L3, and coexistence of classical hepatocellular carcinoma. The accuracy of the formula was validated in bootstrap samples that were created by resampling of 1000 iterations. RESULTS: During a median follow-up period of 504 d, 73 NHNs with a median diameter of 9 mm(interquartile range: 8-12 mm) grew or shrank by 68.5%(fifty nodules) or 20.5%(fifteen nodules), respectively, whereas hypervascularity developed in 38.4%(twenty eight nodules). In the fifteen shrank nodules, twelve nodules disappeared, while 11.0%(eight nodules) were stable in size but acquired vascularity. A generalized estimating equation analysis selected five explanatories from the thirteen variables as significant factors to predict NHN progression. The estimated regression coefficients were 0.36 for age, 6.51 for lower signal intensity in arterial phase, 8.70 or 6.03 for positivity of hepatitis B virus or hepatitis C virus, 9.37 for des-γ-carboxy prothrombin, and-4.05 for fat deposition. A formula incorporating the five coefficients revealed sensitivity, specificity, and accuracy of 88.0%, 86.7%, and 87.7% in the formulating cohort, whereas these of 87.2% ± 5.7%, 83.8% ± 13.6%, and 87.3% ± 4.5% in the bootstrap samples. CONCLUSION: These data suggest that the formula helps Gd-EOB-DTPA-MRI detect a trend toward hepatocyte transformation by predicting NHN destiny.展开更多
The most common methods for three-dimensional reconstruction of peripheral nerve fascicles include histological and radiology techniques. Histological techniques have many drawbacks including an enormous manual worklo...The most common methods for three-dimensional reconstruction of peripheral nerve fascicles include histological and radiology techniques. Histological techniques have many drawbacks including an enormous manual workload and poor image registration. Micro-magnetic resonance imaging（Micro-MRI）, an emerging radiology technique, has been used to report results in the brain, liver and tumor tissues. However, micro-MRI usage for obtaining intraneural structures has not been reported. The aim of this study was to present a new imaging method for three-dimensional reconstruction of peripheral nerve fascicles by ~1T micro-MRI. Freshly harvested sciatic nerve samples from an amputated limb were divided into four groups. Two different scanning conditions（Mannerist Solution/GD-DTPA contrast agent, distilled water） were selected, and both T1 and T2 phases programmed for each scanning condition. Three clinical surgeons evaluated the quality of the images via a standardized scale. Moreover, to analyze deformation of the two-dimensional image, the nerve diameter and total area of the micro-MRI images were compared after hematoxylin-eosin staining. The results show that rapid micro-MRI imaging method can be used for three-dimensional reconstruction of the fascicle structure. Nerve sample immersed in contrast agent（Mannerist Solution/GD-DTPA） and scanned in the T1 phase was the best. Moreover, the nerve sample was scanned freshly and can be recycled for other procedures. MRI images show better stability and smaller deformation compared with histological images. In conclusion, micro-MRI provides a feasible and rapid method for three-dimensional reconstruction of peripheral nerve fascicles, which can clearly show the internal structure of the peripheral nerve.展开更多
Purpose: To describe the magnetic resonance imaging(MRI)features of orbital rhabdomyosarcoma(RMS).Methods: Thirty-nine patients with histopathologically confirmed orbital RMS were retrospectively reviewed. All patient...Purpose: To describe the magnetic resonance imaging(MRI)features of orbital rhabdomyosarcoma(RMS).Methods: Thirty-nine patients with histopathologically confirmed orbital RMS were retrospectively reviewed. All patients underwent orbital conventional MRI, including axial, sagittal,and coronal T1-weighted, T2-weighted, and postcontrast T1-weighted sequences. The location, shape, margin, and MRI signal of the 39 lesions were reviewed. DWI in 15 patients and susceptibility weighted imaging(SWI) in 2 patients were also analyzed.Results: Orbital MRI was available in 39 patients and revealed a soft tissue mass in the orbital region in all cases. Of the 39 patients, the primary tumor sites were limited to the orbital proper in 31 cases, while 28 cases had extraocular muscle invasion and 8 cases had extraorbital invasion. All lesions were unilateral. Thirty-three cases were well-defined soft tissue masses and 6 cases appeared as less well-defined softtissue masses. Thirty-four cases showed homogeneous isointense or slightly hypointense signals on T1-weighted imaging(T1WI) and hyperintense signal on T2-weighted imaging(T2WI) compared with extraocular muscles. Five cases had heterogeneous signals with focal areas of increased signal on T1WI or decreased signal on T2WI, including 1 case with hypointense signal on SWI. The mean apparent diffusion coefficient(ADC) value of the viable part of tumors was(0.925±0.09)×10-3mm2/ s. All cases showed moderate to marked enhancement after contrast administration.Conclusion: Several MRI features-including homogeneous isointense or slightly hypointense signal on T1WI and slightly hyperintense signal on T2WI, relative low ADC values, and moderate to marked enhancement, extraocular muscles invasion, and extraorbital extensionare helpful in the diagnosis of orbital RMS.展开更多
目的:分析自发性脊髓脑脊液漏所致自发性颅内低压(SIH)的临床特点。方法:对42例保守治疗无效的自发性脊髓脑脊液漏所致SIH患者的临床资料和影像学表现进行回顾性分析,并按病程长短分为短病程组(n=27)和长病程组(n=15),比较两组患者的临...目的:分析自发性脊髓脑脊液漏所致自发性颅内低压(SIH)的临床特点。方法:对42例保守治疗无效的自发性脊髓脑脊液漏所致SIH患者的临床资料和影像学表现进行回顾性分析,并按病程长短分为短病程组(n=27)和长病程组(n=15),比较两组患者的临床表现和影像学特征。结果:直立性头痛是SIH患者最典型的临床表现,出现率92.9%(39/42);在长病程组中头痛的发生比例明显低于短病程组(80%与100%,P=0.040)。与短病程组比较,长病程组的腰椎穿刺压力≥60.0 mm H2O的患者数明显增加(60.0%与20.8%,P=0.019),平均腰椎穿刺压力增高[(64.7±42.1)mm H2O与(40.0±33.8)mm H2O,P=0.038)],硬膜下出血的发生率升高(50.0%与11.6%,P=0.018)。所有患者接受CT脊髓造影检查均发现脑脊液漏点,38例为多发漏点,4例仅表现为单个漏点。结论:SIH的临床表现多样,随病程延长,其临床表现和腰椎穿刺压力可有部分改善,影像学检查如颅脑MRI、CT脊髓造影能帮助诊断;病程延长后硬膜下出血的发生概率增加,需积极干预。展开更多
文摘With the widespread of cross-sectional imaging, a growth of incidentally detected focal liver lesions(FLL) has been observed. A reliable detection and characterization of FLL is critical for optimal patient management. Maximizing accuracy of imaging in the context of FLL is paramount in avoiding unnecessary biopsies, which may result in post-procedural complications. A tremendous development of new imaging techniques has taken place during these last years. Nowadays, Magnetic resonance imaging(MRI) plays a key role in management of liver lesions, using a radiation-free technique and a safe contrast agent profile. MRI plays a key role in the non-invasive correct characterization of FLL. MRI is capable of providing comprehensive and highly accurate diagnostic information, with the additional advantage of lack of harmful ionizing radiation. These properties make MRI the mainstay for the noninvasive evaluation of focal liver lesions. In this paper we review the state-of-the-art MRI liver protocol, briefly discussing different sequence types, the unique characteristics of imaging non-cooperative patients and discuss the role of hepatocyte-specific contrast agents. A review of the imaging features of the most common benign and malignant FLL is presented, supplemented by a schematic representation of a simplistic practical approach on MRI.
文摘Since its introduction in the 1970’s,magnetic resonance imaging(MRI)has become a standard imaging modality.With its broad and standardized application,it is firmly established in the clinical routine and an essential element in cardiovascular and abdominal imaging.In addition to sonography and computer tomography,MRI is a valuable tool for diagnosing cardiovascular and abdominal diseases,for determining disease severity,and for assessing therapeutic success.MRI techniques have improved over the last few decades,revealing not just morphologic information,but functional information about perfusion,diffusion and hemodynamics as well.Four-dimensional(4D)flow MRI,a time-resolved phase contrast-MRI with three-dimensional(3D)anatomic coverage and velocity encoding along all three flow directions has been used to comprehensively assess complex cardiovascular hemodynamics in multiple regions of the body.The technique enables visualization of 3D blood flow patterns and retrospective quantification of blood flow parameters in a region of interest.Over the last few years,4D flow MRI has been increasingly performed in the abdominal region.By applying different acceleration techniques,taking 4D flow MRI measurements has dropped to a reasonable scanning time of 8 to 12 min.These new developments have encouraged a growing number of patient studies in the literature validating the technique’s potential for enhanced evaluation of blood flow parameters within the liver’s complex vascular system.The purpose of this review article is to broaden our understanding of 4D flow MRI for the assessment of liver hemodynamics by providing insights into acquisition,data analysis,visualization and quantification.Furthermore,in this article we highlight its development,focussing on the clinical application of the technique.
文摘AIM: To establish a prognostic formula that distinguishes non-hypervascular hepatic nodules(NHNs) with higher aggressiveness from less hazardous one. METHODS: Seventy-three NHNs were detected in gadolinium ethoxybenzyl diethylene-triamine-pentaaceticacid magnetic resonance imaging(Gd-EOB-DTPA-MRI) study and confirmed to change 2 mm or more in size and/or to gain hypervascularity. All images were interpreted independently by an experienced, board-certified abdominal radiologist and hepatologist; both knew thatthe patients were at risk for hepatocellular carcinoma development but were blinded to the clinical information. A formula predicting NHN destiny was developed using a generalized estimating equation model with thirteen explanatory variables: age, gender, background liver diseases, Child-Pugh class, NHN diameter, T1-weighted imaging/T2-weighted imaging detectability, fat deposition, lower signal intensity in arterial phase, lower signal intensity in equilibrium phase, α-fetoprotein, des-γ-carboxy prothrombin, α-fetoprotein-L3, and coexistence of classical hepatocellular carcinoma. The accuracy of the formula was validated in bootstrap samples that were created by resampling of 1000 iterations. RESULTS: During a median follow-up period of 504 d, 73 NHNs with a median diameter of 9 mm(interquartile range: 8-12 mm) grew or shrank by 68.5%(fifty nodules) or 20.5%(fifteen nodules), respectively, whereas hypervascularity developed in 38.4%(twenty eight nodules). In the fifteen shrank nodules, twelve nodules disappeared, while 11.0%(eight nodules) were stable in size but acquired vascularity. A generalized estimating equation analysis selected five explanatories from the thirteen variables as significant factors to predict NHN progression. The estimated regression coefficients were 0.36 for age, 6.51 for lower signal intensity in arterial phase, 8.70 or 6.03 for positivity of hepatitis B virus or hepatitis C virus, 9.37 for des-γ-carboxy prothrombin, and-4.05 for fat deposition. A formula incorporating the five coefficients revealed sensitivity, specificity, and accuracy of 88.0%, 86.7%, and 87.7% in the formulating cohort, whereas these of 87.2% ± 5.7%, 83.8% ± 13.6%, and 87.3% ± 4.5% in the bootstrap samples. CONCLUSION: These data suggest that the formula helps Gd-EOB-DTPA-MRI detect a trend toward hepatocyte transformation by predicting NHN destiny.
基金supported by grants from the National Key Research and Development Plan of China,No.31670986(to QTZ)the Science and Technology Project of Guangdong Province of China,No.2014B020227001,2017A050501017(to QTZ)the Science and Technology Project of Guangzhou of China,No.201807010082(to QTZ),201704030041(to JQ)
文摘The most common methods for three-dimensional reconstruction of peripheral nerve fascicles include histological and radiology techniques. Histological techniques have many drawbacks including an enormous manual workload and poor image registration. Micro-magnetic resonance imaging（Micro-MRI）, an emerging radiology technique, has been used to report results in the brain, liver and tumor tissues. However, micro-MRI usage for obtaining intraneural structures has not been reported. The aim of this study was to present a new imaging method for three-dimensional reconstruction of peripheral nerve fascicles by ~1T micro-MRI. Freshly harvested sciatic nerve samples from an amputated limb were divided into four groups. Two different scanning conditions（Mannerist Solution/GD-DTPA contrast agent, distilled water） were selected, and both T1 and T2 phases programmed for each scanning condition. Three clinical surgeons evaluated the quality of the images via a standardized scale. Moreover, to analyze deformation of the two-dimensional image, the nerve diameter and total area of the micro-MRI images were compared after hematoxylin-eosin staining. The results show that rapid micro-MRI imaging method can be used for three-dimensional reconstruction of the fascicle structure. Nerve sample immersed in contrast agent（Mannerist Solution/GD-DTPA） and scanned in the T1 phase was the best. Moreover, the nerve sample was scanned freshly and can be recycled for other procedures. MRI images show better stability and smaller deformation compared with histological images. In conclusion, micro-MRI provides a feasible and rapid method for three-dimensional reconstruction of peripheral nerve fascicles, which can clearly show the internal structure of the peripheral nerve.
文摘Purpose: To describe the magnetic resonance imaging(MRI)features of orbital rhabdomyosarcoma(RMS).Methods: Thirty-nine patients with histopathologically confirmed orbital RMS were retrospectively reviewed. All patients underwent orbital conventional MRI, including axial, sagittal,and coronal T1-weighted, T2-weighted, and postcontrast T1-weighted sequences. The location, shape, margin, and MRI signal of the 39 lesions were reviewed. DWI in 15 patients and susceptibility weighted imaging(SWI) in 2 patients were also analyzed.Results: Orbital MRI was available in 39 patients and revealed a soft tissue mass in the orbital region in all cases. Of the 39 patients, the primary tumor sites were limited to the orbital proper in 31 cases, while 28 cases had extraocular muscle invasion and 8 cases had extraorbital invasion. All lesions were unilateral. Thirty-three cases were well-defined soft tissue masses and 6 cases appeared as less well-defined softtissue masses. Thirty-four cases showed homogeneous isointense or slightly hypointense signals on T1-weighted imaging(T1WI) and hyperintense signal on T2-weighted imaging(T2WI) compared with extraocular muscles. Five cases had heterogeneous signals with focal areas of increased signal on T1WI or decreased signal on T2WI, including 1 case with hypointense signal on SWI. The mean apparent diffusion coefficient(ADC) value of the viable part of tumors was(0.925±0.09)×10-3mm2/ s. All cases showed moderate to marked enhancement after contrast administration.Conclusion: Several MRI features-including homogeneous isointense or slightly hypointense signal on T1WI and slightly hyperintense signal on T2WI, relative low ADC values, and moderate to marked enhancement, extraocular muscles invasion, and extraorbital extensionare helpful in the diagnosis of orbital RMS.
文摘目的:分析自发性脊髓脑脊液漏所致自发性颅内低压(SIH)的临床特点。方法:对42例保守治疗无效的自发性脊髓脑脊液漏所致SIH患者的临床资料和影像学表现进行回顾性分析,并按病程长短分为短病程组(n=27)和长病程组(n=15),比较两组患者的临床表现和影像学特征。结果:直立性头痛是SIH患者最典型的临床表现,出现率92.9%(39/42);在长病程组中头痛的发生比例明显低于短病程组(80%与100%,P=0.040)。与短病程组比较,长病程组的腰椎穿刺压力≥60.0 mm H2O的患者数明显增加(60.0%与20.8%,P=0.019),平均腰椎穿刺压力增高[(64.7±42.1)mm H2O与(40.0±33.8)mm H2O,P=0.038)],硬膜下出血的发生率升高(50.0%与11.6%,P=0.018)。所有患者接受CT脊髓造影检查均发现脑脊液漏点,38例为多发漏点,4例仅表现为单个漏点。结论:SIH的临床表现多样,随病程延长,其临床表现和腰椎穿刺压力可有部分改善,影像学检查如颅脑MRI、CT脊髓造影能帮助诊断;病程延长后硬膜下出血的发生概率增加,需积极干预。
