腔隙性脑梗死的MRI与CT的诊断价值

目的:探讨腔隙性脑梗死的影像学特点及其临床意义,比较MRI和CT的诊断价值。方法:对120例经临床、MRI诊断明确为腔隙性脑梗死患者的病灶形态大小、部位、数量进行统计。结果:①120例行MRI检查患者共发现病灶890个,最多见于豆状核(占40.8%),其次为放射冠、丘脑、内囊、尾状核、桥脑,可为圆形、椭圆形、条索状病灶。②32例既做CT,又做MRI患者中,MRI检出的病灶数为CT的5.1倍,其中绝大多数CT漏检病灶直径≤5mm或位于幕下。结论:①腔隙性脑梗死常为多发,且第一次临床发病时多数患者颅内已存在无症状性腔隙性脑梗死病灶;②腔隙性脑梗死灶易为CT忽略,尤其是幕下病灶或≤5mm的病灶,这是造成既往文献报道腔隙性脑梗死好发部位差异较大的一个主要原因;③尽管腔隙性脑梗死病灶较小(≤10mm),但大部分(60.0%)急性期存在在周边水肿,需要相应的临床治疗。     

Ventilation imaging of the lung: Comparison of hyperpolarized helium-3 MR imaging with Xe-133 scintigraphy

RATIONALE AND OBJECTIVES: To compare hyperpolarized helium-3 (HHe) magnetic resonance imaging (MRI) of the lung with standard Xe-133 lung ventilation scintigraphy. MATERIALS AND METHODS: We performed a retrospective review of 15 subjects who underwent HHe MRI and Xe-133 lung ventilation imaging. Coronal MRI sections were acquired after a single inhalation of HHe gas, and standard posterior planar lung ventilation scintigraphy was performed during continuous breathing of Xe-133 gas. The first breath scintigram of each patient was compared with a composite MR image composed of the sum of the individual MR images and with the individual helium-3 MR images. Ventilation defects on the two imaging modalities were compared for size, conspicuity, and concordance in presence and location. Assessment was done separately for each of four lung quadrants. RESULTS: Comparing the composite HHe MR images with Xe-133 scintigraphy, ventilation defect size, conspicuity and concordance were the same in 67% (40/60), 63% (38/60), and 62% (37/60) quadrants, respectively. Comparing the individual HHe MR image sections with the Xe-133 ventilation scan, there was concordance between the ventilation defects in 27% (16/60) of quadrants. More defects were identified on the individual HHe MR images in 62% (37/60) of quadrants. CONCLUSION: There was good agreement between composite HHe MR image and first breath Xe-133 scintigraphic images, supporting the widely held assumption that HHe MRI likely depicts first breath lung ventilation.     

PULMONARY BLOOD DISTRIBUTION AFTER TOTAL CAVOPULMONARY CONNECTION OF DIFFERENT TYPES

Objective. To assess the feature of pulmonary blood flow distribution after total cavopulmonary connection (TCPC) of different types, and to provide the selection of the best type .Methods. Thirty-two consecutive survival patients after TCPC underwent radionuclide lung perfusion imaging. According to the radionuclide counts in the left and right lungs, analyses of the distribution of blood flow from superior venous cava (SVC) and inferior venous cava (IVC) and the whole pulmonary blood flow in both lungs were made. All patients were divided into 4 groups by the the anastomosis between IVC and pulmonary artery.Results. Group Ⅰ: The flow ratio of the IVC to left lung was greater than that to the right lung , P≤0. 01; the flow ratio of the SVC to right lung was greater than that to the left lung, P≤0. 01; and the whole pulmonary blood flow went dominantly to the left lung, P≤0. 05, which is not in line with physiological distribution. Group Ⅱ: the flows from the SVC and IVC were mixed in the middle of     

Efficient high-frequency body coil for high-field MRI.

The use of body coils is favored for homogeneous excitation, and such coils are often paired with surface coils or arrays for sensitive reception in many MRI applications. While the body coil's physical size and resultant electrical length make this circuit difficult to design for any field strength, recent efforts to build efficient body coils for applications at 3T and above have been especially challenging. To meet this challenge, we developed an efficient new transverse electromagnetic (TEM) body coil and demonstrated its use in human studies at field strengths up to 4 T. Head, body, and breast images were acquired within peak power constraints of <8 kW. Bench studies indicate that these body coils are feasible to 8 T. RF shimming was used to remove a high-field-related cardiac imaging artifact in these preliminary studies. P41RR13230     

In vivo quantification of fluorescent molecular markers in real-time: A review to evaluate the performance of five existing methods

With the advent of molecular-targeted fluorescent markers, there is a renewed interest in fluorescence quantification methods that are based on continuous wave excitation and multi-spectral image acquisition. However, little is known about their in vivo quantification performance. We reviewed the performance of five selected methods by analytically describing these and varying input parameters of irradiance, excitation geometry, collection efficiency, autofluorescence, melanin content, blood volume, blood oxygenation and tissue scattering using optical properties representing those for human skin. We identified one method that corrects for variations in all parameters. This requires image acquisition before and after marker administration, under identical geometry. Hence, it is suited for applications where the site of interest can be relocated (e.g. anaesthetized animals and dermatology). For applications where relocation is not possible, we identified a second method where the uncertainty in the fluorescence signal was ±20%. Hence, use of these methods can substantially aid in vivo fluorescence quantification compared to use of the raw fluorescence signal, as this changed by more than 3 orders of magnitude. Since these methods can be computed in real-time, they are of particular interest for applications where direct feedback is critical, as diagnostic screening or image-guided surgery.     

18氟-氟化脱氧葡萄糖在下咽部肿瘤诊断中的作用

目的：研究^18氟—氟化脱氧葡萄糖(^18F-FDG)在下咽部肿瘤诊断中的作用。方法：20例下咽部肿瘤患者均接受^18F-FDG检查及CT、全组内镜(食管、咽喉、气管镜)检查。结果：20例下咽部肿瘤患者^18F-FDG检查结果显示：2例阴性；18例肿瘤原发部位有同位素浓集，其中5例伴异位同位素浓集。对此5例患者进一步临床、病理检查证实：1例食管部占位，2例肺部病变，2例为良性改变。^18F-FDG检查结果显示的病变范围与CT、内镜检查相符。结论：^18F-FDG检查可以提高下咽部肿瘤、尤其是隐匿的并发肿瘤诊断的准确性，明确病变范围，为临床治疗提供依据；同时又是一个简单、易行的下咽部肿瘤的随访检查手段。     

兔眼眶植入羟基磷灰石义眼台血管化的MRI评价

目的用MRI研究兔眼眶内植入羟基磷灰石（hydroxyapatite，HA）义眼台血管化过程，探讨义眼台血管化MRI表现和特点。方法12只新西兰白兔眼眶内植入直径12mmHA义眼台，于术后第2、3、4、5、6周对所有手术兔行双眼MR平扫及钆喷替酸葡甲胺（Gd-DTPA）增强扫描，计算义眼台强化区体积与义眼台体积比值（VE／VHA），对结果用单因素方差分析。并于第2、4周采用随机数字法抽取2只，第6周对剩余动物义眼台行组织病理学检查。结果术后第2、3、4、5、6周VE／VHA值分别为0．570±0．055；0．787±0．036；0．995±0．014；1．000±0．000；1．000±0．000。第2、3、4周VE／VHA值逐渐增加，均数间比较差异有统计学意义（F=233．094，P=0），第4、5、6周均数间比较差异无统计学意义（F=0．686，P=0．520）。术后2周病理显示义眼台周边有纤维血管生长，第4、6周整个义眼台完全血管化。结论MRI可直观、准确地评价义眼台血管化的程度和范围。     

ENDOSCOPIC MICROVASCULAR ARCHITECTURE OF THE PORTAL HYPERTENSIVE GASTRIC MUCOSA ON NARROW BAND IMAGING

Background: We evaluated the endoscopic microvascular architecture of the gastric mucosa in portal hypertension patients using the prototype of narrow band imaging (NBI). Material and Methods: The study included 103 Helicobacter pylori‐negative patients with chronic liver disease (22 without portal hypertension (group 1), 81 with portal hypertension (group 2)). Results: (i) Abnormality of collecting venules, reddening mucosa, red spots, a mosaic‐like pattern, and gastric antral vascular ectasia (GAVE) were observed on the gastric mucosa, and an obscure change in collecting venules (73% vs 14%; P < 0.001), reddening mucosa (49% vs 5%; P < 0.001), red spots (36% vs 5%; P < 0.01) and a mosaic‐like pattern (40% vs 5%; P < 0.01) were more frequently observed in group 2 than in group 1. (ii) On magnifying endoscopy with NBI, the mucosa with an obscure change in collecting venules was demonstrated as dilation of the capillaries surrounding the gastric pits in various degrees, and reddening mucosa was observed as extended and swollen gastric pits and various degrees of dilated and convoluted capillaries surrounding the gastric pits. Red spots were demonstrated as extended and swollen gastric pits, dilated and convoluted capillaries surrounding the gastric pits, and intramucosal hemorrhage around these capillaries. GAVE was recognized as partial and marked dilatation of the capillaries surrounding the gastric pits. Conclusion: Abnormality of collecting venules, swelling of gastric pits, dilatation of capillaries surrounding the gastric pits, intramucosal hemorrhage around capillaries, and partial and marked dilatation of the capillaries were observed on the gastric mucosa in portal hypertension patients.     

动态对比增强灌注磁共振成像在颅脑肿瘤的应用

动态对比增强灌注磁共振(MR)成像能提供非侵袭、生理状态下的脑组织微循环血供图，通过计算正常脑组织及肿瘤组织的局部血容量，评估肿瘤组织的血供状态；并有助于评估胶质瘤病理学级别的高低，确定肿瘤穿刺活检的部位，以及对胶质瘤、单发脑转移瘤、淋巴瘤和其他脑肿瘤切除放疗后复发与放射性坏死的诊断和鉴别诊断等；但在颅内脑外肿瘤及伴有血脑屏障严重破坏的脑肿瘤诊断仍存在一定的不足。