垂体的半剂量Gd—DTPA增强磁共振成像研究：与全剂量及手术病理对…

评价半剂量对比增强ＭＲＩ对正常及异常垂体的显示能力。ＭＲ检查６１例垂体，包括９例正常垂体，３７例垂体瘤，７例为垂体瘤手术后，２例γ刀术的一，尿崩症５例，原发性空蝶鞍１例。６１例垂体中１３例采用全剂量，４８例采用半剂量增强检查。     

Gd-DTPA增强的MRI在脑转移瘤诊断中的应用

目的探讨Gd-DTPA增强MRI对脑转移瘤的诊断价值及意义。方法回顾分析100例脑部转移瘤病人的平扫和增强MRI资料。结果100例脑转移瘤病人,平扫检出198个转移病灶,增强扫描检出354个转移病灶。平扫检出坏死囊变病灶85个,增强扫描检出183个。平扫检出病灶最小直径0.8cm,增强扫描检出病灶最小直径0.3cm,98例增强后可清晰显示病灶边界。16例没有症状的病人平扫7例未显示病灶,增强后均发现有转移病灶。结论Gd-DTPA是一种安全的MRI对比剂,增强MRI在显示脑转移瘤的大小、数目、边界、内部结构及位置等方面具有明显优势,可以帮助早期诊断。     

三倍量国产钆喷替酸葡甲胺增强MRI探查脑转移瘤的研究

目的 评价３倍量（０．３ｍｍｏｌ／ｇ）国产钆喷替酸葡甲胺（Ｇｄ－ＤＴＰＡ）增强ＭＲＩ探查脑转移瘤的效果。方法 用国产Ｇｄ－ＤＴＰＡ３倍量增加ＭＲＩ检查５５例怀疑脑转移瘤的患者。对ＭＲ扫描所见进行定性,定量分析。结果 ３倍量增强比常规量增强扫描发现了理多的转移病灶,分别为３７及１７５个。对３倍量增强扫描多发现的１３８个病灶的定量分析表明,３倍量增强使病灶的相对信号强度明显增高。尤其值得指出的是,２     

大剂量对比剂团注在MRI检查中应用

目的：探讨大剂量对比剂注射器团注在脑转移瘤及其血管成像中的临床意义。方法：对35例脑转移瘤患者行MR平扫和增强扫描作为对照，其中26例脑转移瘤患者增强扫描分别采用单剂量手推方式注射(10ml和大剂量注射器团注，并对图像做对比分析。对22例体部血管病变患者和15例肝、肾移植患者及供体行常规扫描后的增强血管成像(enhancedMRA)。快速大剂量团注(20～40ml扫描以1．5～3ml／s流率经上肢大静脉注射造影，造影前根据病灶和血管大小，首先预设置流率、流量及注射时间，再对所选择的病变区域或血管行快速动态扫描和延迟扫描。结果：35例均已确诊有原发病灶的脑转移瘤忠者中23例经手术病理证实，12例经活检病理证实。19例体部血管病变经DSA证实。所有检查均获成功，且大剂量注射器团注组对病变显示优于小剂量手推组。结论：大剂量的注射冕团注能更清晰显示病灶数目和病灶大小、数目和病灶内钙化、坏死以及供给血管情况，为临床提供精确的诊断。     

脑转移癌的诊断:双倍剂量延迟CT扫描法(DDD—CT)与MR增强扫描法的对比

用高剂量(74～84.6g)碘造影剂注射,1小时后进行CT 检查(DDD-CT)能较敏感的检出脑转移癌病灶。作者对23例经DDD-CT 检查后疑有颅脑转移癌或是单发病灶的患者再进行MR 增强扫描检查,比较两项检查结果。作者见到,对于典型脑实质内转移癌病灶,MR 增强扫描发现67个,T_2加权象发现40个,DDD-CT 发现37个。对于可疑脑转移癌的病灶检出,DDD-CT 与MR 增强扫描相接近。作者注意到,T_2加权象检出可疑病灶较多,检出典型脑转移癌病灶较少,曾认为是典型的病灶者,MR 增强扫描证实有些不符合脑转移癌的诊断,说明T_2加权象识别脑转移癌无特异性。     

颅内海绵状血管瘤的影像诊断

目的：分析颅内海绵状血管瘤的ＣＴ和ＭＲＩ征象，以提高对其的认识。材料和方法：经病理证实的海绵状血管瘤３２例，２６例作ＣＴ检查，３０例作ＭＲＩ检查。结果：颅内海绵状血管瘤多为单发，脑内海绵状血管瘤多于脑外。ＣＴ平扫病灶呈高密度或稍高密度，增强扫描病灶呈轻至中度强化。ＭＲＩＴ２ＷＩ常显示海绵状血管瘤核心为混杂高信号，周边有一圈环状低信号。结论：ＭＲＩ对微小病灶的显示较ＣＴ优越，ＣＴ和ＭＲＩ结合是诊断海绵状血管瘤的有效方法，能全面提供诊断资料。     

MRI单、双倍剂量与双倍剂量联合MT扫描对脑转移瘤的显示价值

目的 对比3DT1-FLASH单倍剂量、双倍剂量、双倍剂量联合磁化传递(MT)增强扫描三种方法对脑转移瘤的显示价值.方法 对60例脑转移瘤患者行MRI增强扫描,每种方法各20例.分别测量图像组织的信噪比(SNR)、转移瘤的SNR、转移瘤的对比噪声比(CNR),并利用5分利克特表对混合信号脑转移瘤(病灶一般＞5 mm,实质部分发生囊变、坏死,信号混杂)和单一信号转移瘤(病灶一般＜5 mm,实质部分没有囊变、坏死,信号单一)的显示程度分别进行主观评价.结果 双倍剂量联合MT扫描中转移瘤的SNR值和CNR值最高,双倍剂量扫描中转移瘤的SNR和CNR值次之,双倍剂量联合MT扫描与单倍剂量扫描之间的差异具有统计学意义(P＜0.05).主观评价三组扫描方法对两种转移瘤的成像质量,差异具有统计学意义(P＜0.05),双倍剂量联合MT扫描对单一信号的小转移瘤显示最好;双倍剂量扫描对混合信号的大转移瘤成像质量最好.结论 双倍剂量增强扫描和联合MT技术扫描对不同大小的脑转移瘤显示价值不同.     

脑肿瘤的对比剂增强

脑肿瘤ＣＴ、ＭＲＩ强化的机制相同，均由肿瘤破坏了血脑屏障，使对比剂从血管内渗透到肿瘤组织的细胞外间隙引起，此外，肿瘤血管内的对比剂也会产生一定的强化，增强ＭＲＩ在很多方面优于增强ＣＴ，因此在脑肿瘤的检查中增强ＭＲＩ已大量取代了增强ＣＴ检查，ＭＲＩ对比剂的常规剂量为０．１ｍｍｏｌ／ｋｇ，使用０．３ｍｍｏｌ／ｋ，使用０．３ｍｍｏｌ／ｋｇ的大剂量不但可以提高脑内转移瘤的检出率，还能更准确地显示胶质瘤的范     

脑静脉血管瘤的MRI及MRA

目的：探讨颅内静脉血管瘤的ＭＲＩ和ＭＲＡ影像学表现及诊断和鉴别诊断。材料和方法：应用ＳｉｅｍｅｎｓＭｅｇｎｅｔｉｏｎＶｉｓｉｏｎ１．５Ｔ超导系统对诊断静脉血管瘤（ＶＡ）２０例进行分析。ＭＲＩ扫描用ＳＥＴ１和ＴｕｒｂｏＳＥＴ２加权序列。ＭＲＡ采用ｔｏｆ－ｔｉ３Ｄ－ｍｕｌｔｉ－ｓｌａｂ－ｔｒａ－ｔｕｎ序列。１６例作增强Ｔ１加权及ＭＲＡ检查。血管重建采用ＭＩＰ技术。有１１例曾行ＣＴ检查，１例行手术治疗。结果：所有病例均由ＭＲ检查作出首诊。Ｔ１加权１８例显示扩张引流静脉呈点条状低信号影，有２例未显示，经增强后显示，并有部分髓静脉显示。Ｔ２加权引流静脉多呈高信号，个别呈低信号。较大的ＶＡ亦可显示髓质静脉。ＭＲＡ１５例显示异常血管，典型的表现为脑实质内见为数不等的髓质静脉呈伞状汇入一根异常扩张的引流静脉，整个形态似“水母头”。１例ＭＲＡ未显示病灶。结论：ＭＲ是诊断ＶＡ最好的影像方法，ＭＲＡ有助于确诊本病。增强ＭＲＩ及ＭＲＡ可提高ＶＡ的检出率     

国产Gd-DTPA大剂量增强MRI探查脑转移瘤的临床研究

目的探讨国产Gd-DTPA三倍量（0.3mmol/kg）增强MRI检查脑转移瘤时病灶体积与病灶检出的关系。方法用国产Gd-DTPA大剂量增强MRI检查70例脑转移瘤患者。先行平扫,然后静脉注射常规量(0.1mmol/kg)国产Gd-DTPA。注射后即刻行T1WI扫描、20min后行延迟扫描。距第一次注射30min后,再注射0.2mmol/kg的Gd-DTPA,从而达到累积剂量0.3mmol/kg。第二次注射后即刻及20min后分别行T1WI扫描。对MR扫描所见进行定性、定量分析。结果三倍量增强比常规量增强扫描发现了更多的转移病灶（86→363,P＜0.01）。对于直径大于10mm的转移瘤病灶,三倍量增强的检出率和其它扫描序列之间没有显著性差异。而对于直径小于10mm的转移瘤病灶,三倍量增强的检出率和其它扫描序列之间有显著性差异（P＜0.05）。尤其对于直径小于5mm的病灶,三倍量增强扫描可以检出89.8%～97.8%的病灶,而常规量增强扫描仅能检出0.4%～0.9%的病灶（P＜0.01）。结论国产Gd-DTPA三倍量(0.3mmol/kg)增强可提高脑转移瘤病灶的检出率,尤其对于直径小于5mm的病灶效果更好。     

The effect of contrast dose,imaging time,and lesion size in the MR detection of intracerebral metastasis.

PURPOSETo evaluate the effect of MR contrast dose versus delayed imaging time on the detection of metastatic brain lesions based on lesion size.METHODSContrast MR examinations with gadoteridol were obtained in 45 patients with brain metastases. The patients were divided into two groups: 16 received cumulative standard dose (0.1 mmol/kg) and 29 received cumulative triple dose (0.3 mmol/kg). Both groups were evaluated at two dose levels (lower dose and higher dose) with two separate injections. Each patient received an initial bolus injection of either 0.05 (cumulative standard dose) or 0.1 (cumulative triple dose) mmol/kg of gadoteridol to reach the lower-dose level and underwent imaging immediately and 10 and 20 minutes later. Thirty minutes after injection, an additional bolus injection of 0.05 (cumulative standard dose) or 0.2 (cumulative triple dose) mmol/kg was administered to reach the cumulative higher-dose level (cumulative standard dose, 0.1 mmol/kg; cumulative triple dose, 0.3 mmol). Images were acquired immediately.RESULTSThere was no difference in the detection rate for lesions larger than 10 mm among T2-weighted, lower-dose immediate and delayed, or immediate higher-dose images in both study groups. Lesions smaller than 10 mm had improved detection with delayed imaging in both study groups; however, the immediate higher-dose studies still had the highest detection rate.CONCLUSIONIn the evaluation of small central nervous system metastases, either delayed imaging after the injection of standard contrast dose or higher contrast dose may improve their detection, and therefore affect clinical management. Higher contrast dose (cumulative triple dose) studies appear to be more effective than delayed imaging with standard dose.     

MR evaluation of CNS tumors: dose comparison study with gadopentetate dimeglumine and gadoteridol

In phase II and III trials of gadoteridol (Gd-HP-D03A), a new nonionic, low-osmolar contrast agent, 40 patients with intracranial neoplasms underwent magnetic resonance (MR) imaging with experimental doses of 0.05-0.3 mmol/kg. Fifteen patients also underwent contrast studies with the standard dose (0.1 mmol/kg) of gadopentetate dimeglumine. Both gadopentetate dimeglumine and gadoteridol appear to have a similar effect when given in equal doses (0.1 mmol/kg, n = 5). Lesion enhancement and delineation were better at higher experimental doses (0.2 or 0.3 mmol/kg, n = 7) and worse at a lower experimental dose (0.05 mmol/kg, n = 3). Quantitative analysis of 10 lesions examined with identical imaging protocols revealed a directly proportional relationship (r = .975) between lesion contrast ratio and dose over a range of 0.05-0.3 mmol/kg. Phantom experiments support the clinical results. Improved enhancement, detection, and delineation of central nervous system (CNS) neoplasms resulting from increased injected doses of gadoteridol have the potential to be clinically significant and may justify the possibly higher cost of increased contrast material dosage. Lower doses may not be adequate for the evaluation of most CNS tumors.     

Low-field interventional MRI in neurosurgery: finding the right dose of contrast medium

MRI is increasingly being used as an interventional tool in neurosurgery. The field strength of “intraoperative” MR systems is usually lower than that of imagers commonly used for diagnostic purposes. However, lesion enhancement and apparent lesion extent depend on field strength. The aim of this study was to compare the contrast between intracranial, contrast-enhancing space-occupying lesions and the surrounding white matter obtained with low-field (0.2 T) and high-field (1.5 T) MR imaging and to find the contrast medium dosage for low-field MRI that produces the same lesion-to-white-matter contrast as the one obtained with high-field MRI after the administration of a standard dose of the contrast medium. A total of 38 patients with intracranial metastases or high-grade glioma were enrolled in this study. T1-weighted spin-echo sequences were acquired. High-field (1.5 T) studies were performed after the i. v. administration of 0.1 mmol gadolinium-DTPA /kg body weight. For low-field MRI (0.2 T) a dose escalation technique was used. T1-weighted sequences were repeated after each of three i. v. injections of 0.1 mmol gadolinium-DTPA/kg body weight. Thus, at the low-field examinations three T1-weighted sequences with a contrast medium dosage of 0.1, 0.2 and 0.3 mmol gadolinium-DTPA /kg body weight were obtained. Lesion-to-white-matter contrasts were calculated and compared. The average lesion-to-white-matter contrast obtained with high-field MR examinations was 1.63 (standard deviation 0.32). In the low-field MR examinations the average lesion-to-white-matter contrast was 1.34 (0.2) after a single dose, 1.57 (0.2) after a double dose, and 1.71 (.19) after a triple dose of contrast medium. The lesion-to-white-matter contrast of the high-field MR examination after a single dose of contrast medium was significantly higher than that of the low-field study after a single dose (P < 0.0001), but did not differ significantly from the low-field studies after a double (P = 0.28) or a triple dose (P = 0.17) of contrast medium. In a series of patients with contrast-enhancing space occupying brain lesions low-field MRI (0.2 T) after a double dose of contrast medium yielded the same lesion-to-white-matter contrasts as high-field MRI (1.5 T) after a standard dose. This is an important finding to avoid errors in intraoperative MRI due to the immanently lower degree of lesion enhancement in low-field MR imaging. Received: 14 September 1999 Accepted: 15 February 2000     

High-dose gadoteridol in MR imaging of intracranial neoplasms.

Twelve patients with a high suspicion of brain metastases by previous clinical or radiologic examinations were studied in a phase III investigation with magnetic resonance (MR) imaging at 1.5 T after a bolus intravenous injection of 0.1 mmol/kg gadoteridol followed at 30 minutes by a second bolus injection of 0.2 mmol/kg gadoteridol. All lesions were best demonstrated (showed greatest enhancement) at the 0.3-mmol/kg (cumulative) dose, with image analysis confirming signal intensity enhancement in the majority of cases after the second gadoteridol injection. More lesions were detected with the 0.3-mmol/kg dose than with the 0.1-mmol/kg dose, and more lesions were detected with the 0.1-mmol/kg dose than on precontrast images. In this limited clinical trial, high-dose gadoteridol injection (0.3-mmol/kg cumulative dose) provided improved lesion detection on MR images specifically in intracranial metastatic disease.     

Enhancement of cerebral diseases: how much contrast agent is enough? Comparison of 0.1, 0.2, and 0.3 mmol/kg gadoteridol at 0.2 T with 0.1 mmol/kg gadoteridol at 1.5 T

RATIONALE AND OBJECTIVES: To determine the clinical dose of gadoteridol (ProHance, Bracco-Byk Gulden) to use for the assessment of blood-brain barrier breakdown on low-field magnetic resonance (MR) scanners that corresponds to a standard dose of gadoteridol on high-field MR scanners. METHODS: This prospective study was carried out at four centers. A total of 138 patients with suspected or known brain diseases underwent a routine head scan comprising precontrast T2-weighted turbo spin-echo and T1-weighted spin-echo sequences on a 1.5-T MR scanner. After administration of a standard dose of 0.1 mmol/kg gadoteridol, the T1-weighted scan was repeated after a delay of 15 to 20 minutes. For continuing the examination on a 0.2-T MR scanner (Magnetom OPEN, Siemens), a standard-dose T1 spin-echo sequence was started within 30 to 50 minutes of the first injection. Then two additional T1-weighted low-field sequences were each started 5 minutes after two additional doses of 0.1 mmol/kg gadoteridol. Eighty patients with enhancing lesions underwent an intraindividual comparison. Evaluation of the overall numbers of lesions detected and of lesion size and character was performed on-site as well as off-site by two independent readers. RESULTS: The single-dose, low-field sequence detected significantly fewer enhancing lesions (80/95 lesions; P < 0.05), particularly metastases and infarctions, than did the standard-dose, high-field sequence. No statistically relevant differences (reader 1: P = 1; reader 2: P = 0.8) were found between the double- and triple-dose, low-field sequences and the standard-dose, high-field sequence. Primary brain tumors were detected by all postcontrast sequences irrespective of the dose. CONCLUSIONS: At low field, the clinically equivalent dose to 0.1 mmol/kg gadoteridol at high field is 0.2 mmol/kg. A dose of 0.1 mmol/kg gadoteridol is less effective and cannot be recommended for use on extremely low-field scanners.     

MR Imaging detection of cerebral metastases with a single injection of high-dose gadoteridol

The utility of a single high-dose (0.3 mmol/kg) injection of gadoteridol, a gadolinium chelate, in the detection of brain metastases on magnetic resonance images was studied. Patients (n = 29) with a high suspicion for brain metastases at clinical examination and by history were imaged on two occasions–separated by more than 24 hours and less than 7 days–with a 0.1 mmol/kg contrast agent dose used for the first study and a 0.3 mmol/kg dose for the second. In patients (n = 15) with confirmed brain metastases by clinical, radiologic, and/or histologic criteria, 40 lesions were detected at the 0.3 mmol/kg dose by a single reader blinded to contrast agent dose, compared with 33 lesions at 0.1 mmol/kg, a 21% increase. Three of 15 patients (20%) demonstrated an increase in the number of lesions detected at the higher dose. Region-of-interest analysis of signal intensity measurements showed that lesion contrast (relative to normal brain) improved from 54% at 0.1 mmol/kg to 92% at 0.3 mmol/kg. A 0.3 mmol/kg dose of gadoteridol, administered in a single injection, permits identification of brain metastases not detected at 0.1 mmol/kg. Such information can influence the choice of therapy.     

Suspected non-small cell lung cancer: incidence of occult brain and skeletal metastases and effectiveness of imaging for detection--pilot study

PURPOSE: To estimate the incidence of occult metastases to the brain and skeleton in patients suspected of having non-small cell lung cancer (NSCLC) (stage higher than T1Nomo) with surgically resectable disease, to assess the accuracy of screening magnetic resonance (MR) imaging and radionuclide bone scanning for help in identifying occult metastases, and to determine the effectiveness of a high dose of MR contrast material. MATERIALS AND METHODS: Twenty-nine patients suspected of having NSCLC localized to the lung or to the lung and regional nodes underwent preoperative MR imaging with contrast material enhancement and radionuclide bone scanning for detection of brain or skeletal metastases. Patients were followed up for 12 months to determine the incidence of clinical metastatic disease. RESULTS: Eight (28%) patients had occult metastatic disease to the brain or skeleton. Brain metastases were identified on MR images in five of six patients. Bone metastases were identified on MR images in four of five patients and on bone scans in three of five patients. MR imaging was no more accurate than bone scanning for skeletal evaluation. A high dose of MR contrast material allowed detection of more metastases and of small lesions. CONCLUSION: Contrast-enhanced MR imaging of the brain is indicated for the exclusion of brain metastases in patients with clinically operable known or possible NSCLC and a large (> 3-cm) lung mass. Skeletal imaging may be indicated if an isolated brain metastasis is detected.     

Experience with high-dose gadolinium MR imaging in the evaluation of brain metastases.

PURPOSE: To assess the effectiveness and safety of higher doses of gadoteridol in the MR evaluation of patients with brain metastases. MATERIALS AND METHODS: Thirty-one patients with a clinical suspicion of brain metastases were studied prospectively with gadoteridol, a new, nonionic, low-osmolality contrast agent. Each patient received an initial injection of 0.1 mmol/kg and an additional dose of 0.2 mmol/kg 30 minutes later. Images were obtained before, immediately after, and 10 and 20 minutes after the initial dose. Images also were acquired immediately after the additional dose of gadoteridol. RESULTS: No adverse effects were attributed to the injection of gadoteridol. Four patients' examinations were excluded from analysis because of machine malfunction (two patients) and excessive motion artifact (two patients). Four patients had no detectable metastases. After the additional dose of gadoteridol, there was a marked qualitative improvement in lesion conspicuity and detection. The conspicuity of 80 of 81 lesions was increased in the high-dose studies, and 46 new lesions were detected in 19 of 27 patients. Quantitative image analysis demonstrated a significant increase in normalized mean lesion contrast between the initial-dose and high-dose studies (35 lesions identified in 13 patients, P less than .0001). The additional information gained by high-dose examinations contributed to a potential modification of the treatment in 10 of 27 patients. High-dose examinations increased flow-related artifact in the posterior fossa in 12 of 27 patients. CONCLUSION: Based on our preliminary results, high-dose gadolinium-enhanced MR examinations may have advantages over 0.1 mmol/kg examinations in detecting early and/or small metastases. This may be significant in the management of patients with cerebral metastases.