Follow-up of patients with previous treatment for coarctation of the thoracic aorta: comparison between contrast-enhanced MR angiography and fast spin-echo MR imaging

Regular follow-up is required in patients with previous intervention for coarctation of the aorta to detect recoarctation or aneurysm formation. In this study we describe the findings encountered on routine follow-up exams and we compare the use of contrast-enhanced 3D MR angiography (CE MRA) with fast spin-echo MRI (FSE) to study the thoracic aorta after previous intervention. In 51 consecutive patients previously treated for aortic coarctation, 74 MR studies of the thoracic aorta were performed during a 2-year period using CE MRA and FSE MRI. The thoracic aorta was evaluated for abnormalities of course, caliber, shape, and pathology of side branches. The CE MRA and FSE MRI studies were evaluated side by side by consensus of two reviewers evaluating which MR technique depicted the abnormalities of the thoracic aorta the best. Of 74 exams, six clinically important abnormalities were found: four aneurysms and two restenoses. Two small pseudoaneurysms were missed on the FSE studies. Contrast-enhanced MRA was judged to visualize aortic abnormalities better than FSE (47 of 74 MR studies) especially for the transverse aortic arch, coarctation site, left subclavian artery, and aortic arch configuration. For the ascending aorta and distal descending aorta, CE MRA and FSE performed equally well. Aortic diameters measured at four levels in the first 18 MRI studies showed no significant differences in diameter when measured by FSE or CE MRA (p = not significant). Clinically important abnormalities, such as aneurysm formation and restenosis, can be present years after treatment for aortic coarctation. In the regular follow-up of these patients, CE MRA may provide additional diagnostic information compared with FSE and should be included as part of the routine exam. Received: 3 April 2000; Revised: 5 July 2000; Accepted: 7 July 2000     

Rheumatoid arthritis of the craniocervical region: assessment and characterization of inflammatory soft tissue proliferations with unenhanced and contrast-enhanced CT

The aim of this study was to depict and characterize inflammatory soft tissue proliferations caused by rheumatoid arthritis (RA) in the craniocervical region by unenhanced and contrast-enhanced CT. Computed tomography of the craniocervical region was performed in 35 patients in the axial plane before and after the i. v. administration of contrast material. According to the densities and contrast enhancement of the inflammatory soft tissue proliferations, four groups were classified. Ancillary findings, such as a compression of the dural sac or spinal cord, erosions of the bony structures, and atlantoaxial subluxation, were also evaluated. Inflammatory soft tissue proliferations were depicted in 28 of 35 patients and could be differentiated by unenhanced and contrast-enhanced CT according to the above defined criteria: effusion in 6 patients (17 %); hypervascular pannus in 8 (23 %); hypovascular pannus in 5 (14 %); and fibrous tissue in 9 patients (26 %). A compression of the dural sac was seen in 11 (31 %) patients; 3 of these had neurological symptoms. Erosions of the odontoid process were found in 20 (57 %) patients; 16 (80 %) of these also showed erosions of the atlas. Atlantoaxial subluxation was seen in 11 (31 %) patients. Inflammatory soft tissue proliferations in the craniocervical region caused by RA can be reliably demonstrated and classified by unenhanced and contrast-enhanced CT, which can differentiate between joint effusion and various forms of pannus and depict ancillary findings. Computed tomography is an alternative method for patients unable to undergo an MRI examination. Received: 4 October 1999; Revised: 7 March 2000; Accepted: 14 March 2000     

3T磁共振团注法3D DCE MRA在腹部至下肢血管成像中的应用

目的：探讨3T超高强磁场磁共振团注法三维动态增强MRA（3D DCE MRA）在腹部、盆腔及下肢血管成像中的应用。方法：使用GE EXCITE Ⅱ3.0T双梯度超导磁共振，采用体线圈、移床技术、高压注射器团注对比剂，对30例腹部至下肢血管受检者行3D DCE MRA检查，对所有受检者的原始图像在工作站利用ADW4.2软件进行MIP和REFORMAT重建并进行成像质量的评价。结果：30例受检者的腹部至下肢血管成像均获得满意效果，血管清晰，病变明确，其中12例闭塞性动脉硬化患者经手术证实与3D DCE MRA显示的血管病变相符。结论：3D DCE MRA是一种新的、有效的腹部至下肢血管成像方法。     

GROUNDHOG DAY: CAUSE AND EFFECT AND THE PRIMARY IMPORTANCE OF THE FINITE POPULATION INDUCED BY RANDOMIZATION

The logical structure that enables randomized clinical trials to establish cause and effect is reviewed. Statisticians have a major role to define this structure clearly and to help clinicians apply statistical inference in ways directly related to their trials. Scientific importance of establishing limited cause and effect should be accented rather than inferences to generalized populations beyond the scope of a trial's actual random sampling. Authors of clinical reports should clearly define the randomization-induced populations to which their inferences apply. Careful attention to identifying this population of inference can lead to resolution of some issues commonly debated in the analysis of clinical trials. If formal inferences to generalized populations are attempted, these populations should also be carefully described, the assumed random sampling process should be carefully defined, and appropriate methods should be used that correspond with the assumed random sampling process.     

Measuring contrast sensitivity

Contrast sensitivity defines the threshold between the visible and invisible, which has obvious significance for basic and clinical vision science. Fechner’s 1860 review reported that threshold contrast is 1% for a remarkably wide range of targets and conditions. While printed charts are still in use, computer testing is becoming more popular because it offers efficient adaptive measurement of threshold for a wide range of stimuli. Both basic and clinical studies usually want to know fundamental visual capability, regardless of the observer’s subjective criterion. Criterion effects are minimized by the use of an objective task: multiple-alternative forced-choice detection or identification. Having many alternatives reduces the guessing rate, which makes each trial more informative, so fewer trials are needed. Finally, populations who may experience crowding or target confusion should be tested with one target at a time.     

Neurophysiological adaptations to spaceflight and simulated microgravity

Changes in physiological functions after spaceflight and simulated spaceflight involve several mechanisms. Microgravity is one of them and it can be partially reproduced with models, such as head down bed rest (HDBR). Yet, only a few studies have investigated in detail the complexity of neurophysiological systems and their integration to maintain homeostasis. Central nervous system changes have been studied both in their structural and functional component with advanced techniques, such as functional magnetic resonance (fMRI), showing the main involvement of the cerebellum, cortical sensorimotor, and somatosensory areas, as well as vestibular-related pathways. Analysis of electroencephalography (EEG) led to contrasting results, mainly due to the different factors affecting brain activity. The study of corticospinal excitability may enable a deeper understanding of countermeasures' effect, since greater excitability has been shown being correlated with better preservation of functions. Less is known about somatosensory evoked potentials and peripheral nerve function, yet they may be involved in a homeostatic mechanism fundamental to thermoregulation. Extending the knowledge of such alterations during simulated microgravity may be useful not only for space exploration, but for its application in clinical conditions and for life on Earth, as well.     

水化疗法预防造影剂肾病的效果研究

目的研究水化疗法预防造影剂肾病的效果。方法随机选取2016年6月～2018年6月我院收治的造影剂肾病高危患者60例,依据预防方法分为两组,即氯化钠水化疗法组和复方氯化钠水化疗法组,每组30例,统计分析两组患者的Cr、pH、GFR、HCO3~-、K~+水平、造影剂肾病、二级终点事件发生情况。结果复方氯化钠水化疗法组患者的Cr水平显著低于氯化钠水化疗法组(P0.05),pH、GFR水平均显著高于氯化钠水化疗法组(P0.05),造影剂肾病、二级终点事件发生率为3.3%(1/30)、0,均显著低于氯化钠水化疗法组的13.3%(4/30)、10.0%(3/30)(P0.05)。结论复方氯化钠水化疗法预防造影剂肾病的效果较氯化钠水化疗法好,值得在临床推广。     

Colorectal cancer:Current imaging methods and future perspectives for the diagnosis,staging and therapeutic response evaluation

In the last 10 years the mortality rate of colorectal cancer(CRC)has decreased by more than 20%due to the rising developments in diagnostic techniques and optimization of surgical,neoadjuvant and palliative therapies.Diagnostic methods currently used in the evaluation of CRC are heterogeneous and can vary within the countries and the institutions.This article aims to discuss in depth currently applied imaging modalities such as virtual computed tomography colonoscopy,endorectal ultrasound,computed tomography(CT)and magnetic resonance imaging(MRI)in the diagnosis of CRC.Special focus is put on the potential of recent diagnostic developments as diffusion weighted imaging MRI,MRI biomarkers(dynamic enhanced MRI),positron emission tomography with 2-(fluorine-18)-fluoro-2-deoxy-D-glucose(FDG-PET)combined with computed tomography(PET/CT)and new hepatobiliary MRI contrast agents.The precise role,advantage and disadvantages of these modalities are evaluated controversially in local staging,metastatic spread and treatment monitoring of CRC.Finally,the authors will touch upon the future perspectives in functional imaging evaluating the role of integrated FDG-PET/CT with perfusion CT,MRI spectroscopy of primary CRC and hepatic transit time analysis using contrast enhanced ultrasound and MRI in the detection of liver metastases.Validation of these newer imaging techniques may lead to significant improvements in the management of patients with colorectal cancer.