Fast T1- and T2-weighted pulmonary MR-imaging in patients with bronchial carcinoma

PURPOSE: A prospective study to evaluate the diagnostic potential and limitations of three fast MRI sequences in patients with bronchial carcinoma based on the comparison with spiral CT. MATERIAL AND METHODS: Three fast chest MRI sequences from 20 patients with central or peripheral bronchial carcinoma were evaluated by two observers for relation of tumour to adjacent structures, lymph node enlargement, additional pulmonary lesions and artefacts. The information from MR-imaging was compared with the results from spiral CT. MRI comprised a T1-3D-GRE breath-hold examination ("VIBE", TR/TE 4.5/1.9 ms, flip-angle 12 degrees , matrix 502 x 512, 2.5 mm coronal slices), a breath-hold, T2-HASTE sequence (TR/TE 2000/43 ms, matrix 192 x 256, 10 mm coronal slices) and a respiration-triggered T2-TSE sequence (TR/TE 3000-6000/120 ms, matrix 270 x 512, 6 mm transverse slices). The FOV was adapted individually (380-480 mm). RESULTS: The presence of the primary bronchial carcinoma and infiltration of thoracic structures by tumour tissue could be demonstrated by all sequences. VIBE sequence was more suitable for detecting small pulmonary nodules than the other MRI examinations, but compared to CT still 20% of these lesions were missed. Contrary to VIBE and T2-weighted TSE scans, HASTE sequence was limited in imaging mediastinal lymph nodes due to missing relevant findings in 2/20 patients. HASTE images significantly provided the lowest rate of artefacts in imaging lung parenchyma (P < 0.001 in peripheral parenchyma), but spatial resolution was limited in this sequence. Concerning the differentiation between tumour and adjacent atelectasis (n = 8), T2-weighted TSE imaging was superior to CT and VIBE in all cases and to HASTE sequence in 4/8 patients. CONCLUSION: The combination of VIBE and HASTE sequence allows for an adaequate imaging of thoracic processes in patients with bronchial carcinoma, limited only in visualizing small pulmonary nodules. To obtain more detail resolution and to differentiate tumour tissue from adjacent atelectasis, T2-TSE examination may be added in selected cases.     

Cerebral staging of lung cancer: is one single contrast-enhanced T1-weighted three-dimensional gradient-echo sequence sufficient?

Introduction

Gadolinium-enhanced magnetic resonance imaging (MRI) is the gold standard for cerebral staging in thoracic oncology. We hypothesize that a minimalist examination, consisting of a single contrast-enhanced T1-weighted three-dimensional gradient-echo sequence (CE 3D-GRE), would be sufficient for the cerebral staging of nonsymptomatic lung cancer patients.

Methods

Seventy nonsymptomatic patients (50 % men; 62 years?±?10.2) referred for cerebral staging of a lung cancer were retrospectively included. All underwent a standard 3 T MRI examination with T1, FLAIR, T2* GRE, diffusion, and CE 3D-GRE sequences, for a total examination time of 20 min. The sole CE 3D-GRE (acquisition time: 6 min) was extracted and blindly interpreted by two radiologists in search of brain metastases. Hemorrhagic features of potential lesions and relevant incidental findings were also noted. Discrepant cases were reviewed by a third reader. The full MRI examination and follow-up studies were used as a reference to calculate sensitivity and specificity of the sole CE 3D-GRE.

Results

Thirty-eight point six percent (27 out of 70) of the patients had brain metastases. Performances and reader’s agreement with the sole CE 3D-GRE sequence were excellent for the diagnosis of brain metastases (sensitivity?=?96.3 %, specificity?=?100 %, κ?=?0.91) and incidental findings (sensitivity?=?85.7 %, specificity?=?100 %, κ?=?0.62) but insufficient for the identification of hemorrhages within the metastases (sensitivity?=?33.3 %, specificity?=?85.7 %, κ?=?0.47).

Conclusions

In the specific case of lung cancer, cerebral staging in nonsymptomatic patients can be efficiently achieved with a minimalistic protocol consisting of a single CE 3D-GRE sequence, completed if positive with a T2* sequence for hemorrhagic assessment, thus halving appointment delays.     

Detection of small pulmonary nodules in high-field MR at 3 T: evaluation of different pulse sequences using porcine lung explants

To evaluate two MR imaging sequences for the detection of artificial pulmonary nodules inside porcine lung explants. 67 agarose nodules ranging 3–20 mm were injected into ten porcine lungs within a dedicated chest phantom. The signal on T1-weighted images and radiopacity were adjusted by adding 0.125 mmol/l Gd-DTPA and 1.5 g/l of iodine. A T1-weighted three-dimensional gradient-echo (T1-3D-GRE; TR/TE:3.3/1.1 ms, slice:8 mm, flip-angle:10°) and a T2-weighted half-Fourier fast-spin echo sequence (T2-HF-FSE; TR/TE:2000/66 ms, slice:7 mm, flip-angle:90°) were applied in axial orientation using a 3-T system (Intera, Philips Medical Systems, Best, The Netherlands), followed by CT (16×0.5 mm) as reference. Nodule sizes and locations were assessed by three blinded observers. In nodules of >10 mm, sensitivity was 100% using 3D-GRE-MRI and 94% using the HF-FSE sequence. For nodules 6–10 mm, the sensitivity of MRI was lower than with CT (3D-GRE:92%; T2-HF-FSE:83%). In lesions smaller than 5 mm, the sensitivity declined to 80% (3D-GRE) and 53% (HF-FSE). Small lesion diameters were overestimated with both sequences, particularly with HF-FSE. This study confirms the feasibility of 3 T-MRI for lung nodule detection. In lesions greater than 5 mm, the sensitivity of the 3D-GRE sequence approximated CT (>90%), while sensitivity and PPV with the HF-FSE sequence were slightly inferior.     

MRI of the thorax during whole-body MRI: evaluation of different MR sequences and comparison to thoracic multidetector computed tomography (MDCT)

PURPOSE: To evaluate the accuracy of four MR sequences used as part of a whole-body MRI protocol to detect pulmonary lesions in cancer patients. MATERIALS AND METHODS: A total of 31 oncology patients were imaged in a 1.5T MR scanner (Magnetom Avanto; Siemens Medical Solutions, Germany) for whole-body staging. MR chest imaging included: axial and coronal T2-weighted (T2w)-short-tau inversion-recovery (STIR), axial T2w turbo spin-echo (TSE), and contrast-enhanced (CE) three-dimensional (3D) volumetric interpolated breathhold examination (VIBE). Multidetector computed tomography (MDCT) of the thorax served as the reference standard. The MDCT and MR images were evaluated independently by two radiologists. Comparative analysis was performed per lesion, per lobe, and per patient. Sensitivity, specificity, and predictive values were determined. RESULTS: Compared to MDCT that detected 268 pulmonary lesions ranging from 2 to 75 mm in diameter, the MR sensitivities were 91.1%, 92.5%, 90.8%, and 87.3% for the coronal STIR, the axial STIR, the axial T2w-TSE, and the axial CE 3D-VIBE, respectively. Undetected pulmonary lesions were either calcified or smaller than 10 mm in the axial diameter. With coronal STIR, six false-positive findings were detected; with axial STIR, 14 were detected; with axial T2w-TSE, 10 were detected; and with 3D-VIBE, seven were detected. CONCLUSION: Pulmonary MRI is feasible as part of a whole-body MRI protocol. In our study, STIR images achieved high accuracy compared to chest MDCT for pulmonary lesions of 3 mm in size or larger.     

Magnetic resonance imaging gastrography: evaluation of the dark lumen technique compared with conventional gastroscopy in patients with malignant gastric disease

OBJECTIVES: We sought to demonstrate the feasibility of depicting gastric tumors using magnetic resonance imaging (MRI) while applying the dark lumen technique. The findings were correlated with conventional gastroscopy. In addition, we evaluated the screening for lymph nodes and liver metastases during the same session to identify potential tumor spread. MATERIALS AND METHODS: The study included 15 patients with known malignant gastric disease. Conventional gastrointestinal endoscopy was performed in all patients as gold standard. All patients were examined with computed tomography for tumor staging. MRI was performed using 1 L of tap water as oral contrast agent for all protocols. The MRI program included an axial T1-weighted (T1w; 2D-FLASH) sequence, an axial STIR and T2w (TSE) sequence, and 2 postcontrast T1w (3D coronal /2D axial FLASH) sequences using 0.2 mmol/kg gadolinium diethylenetriaminepenta-acetic acid as intravenously injected contrast agent. Qualitative analysis and comparison with conventional gastroscopy were performed. RESULTS: The images obtained with the postcontrast 3D coronal T1w-FLASH sequence were the most suitable in identifying gastric tumors. Complete correlation with conventional gastroscopy was achieved in 80% of the cases and partial correlation in 13% of the cases. The same imaging sequence was also appropriate for the evaluation of lymph nodes. For the identification of liver metastases, the images obtained with the axial postcontrast T1w 2D-FLASH sequence provided a higher diagnostic confidence as compared with other imaging protocols. CONCLUSIONS: Applying the dark lumen technique through MRI is suitable for imaging gastric tumors and has the potential to become a "one-stop shopping" method because of the possibility for lymph node evaluation and screening for metastases during the same session based on the same images.     

Internal derangements of the temporomandibular joint: comparison of assessment with three-dimensional gradient-echo and spin-echo MRI

Our purpose was to assess the diagnostic accuracy of three-dimensional (3D) gradient-echo (GRE) MRI in the diagnosis of internal derangements of the temporomandibular joint (TMJ). We studied 140 joints in 70 patients with TMJ internal derangements. We obtained 3D-GRE and spin-echo (SE) images in the closed-mouth position; the images were reviewed for disc displacement as well as bone and cartilage abnormalities. The 3D-GRE and SE images were interpreted independently by different radiologists. The sensitivity and specificity of 3D-GRE imaging for assessing mediolateral disc displacement was 100 %, whereas the sensitivity and specificity of sagittal SE images were 82 % and 72 %, respectively (P < 0.001). The 3D-GRE images also demonstrated more bone abnormalities (in 112 condyles or 80 %) than did SE images (in 79 condyles or 56 %) (P < 0.001). Furthermore, 3D-GRE imaging revealed articular cartilage abnormalities in 46 condyles (33 %) that were not visible on SE images. The frequency of pain was significantly higher in joints with bone and cartilage abnormalities (P < 0.05 and P < 0.001, respectively). For assessment of disc displacement, 3D-GRE images were superior to sagittal SE images alone, and comparable to combined sagittal and coronal SE images, while for bone and cartilage abnormalities, they were superior to sagittal and coronal SE images. Received: 8 July 1996 Accepted: 7 November 1996     

Preoperative staging of renal cell carcinoma with inferior vena cava thrombus using multidetector CT and MRI: prospective study with histopathological correlation

OBJECTIVE: To evaluate the accuracy of multidetector computed tomography (CT) and magnetic resonance imaging (MRI) in staging and estimating renal carcinomas with caval thrombus. METHODS: Initially, 23 patients with suspected caval thrombi were admitted into this prospective study. Triphasic CT imaging was performed using a multidetector CT with a reconstructed slice thickness of 2 mm. 3D CT reconstructions were used to improve surgical planning. MRI protocol included: a transversal T1-weighted GE sequence with and without Gd-DTPA, a transversal T2-weighted respiratory-gated TSE, and a coronal T1-weighted GE sequence with Gd-DTPA and fat saturation. In addition, a multiphase 3D angiography was performed after Gd-DTPA injection. Patients were divided into 3 groups: caval thrombus below the insertion of the hepatic veins, within the intrahepatic vena cava, and intra-atrial extension. The results the tumor thrombus extension and staging results of 2 independent readers were correlated with surgical and histopathological staging. RESULTS: Of the 23 patients admitted, CT and MR scans of 14/13 patients respectively were correlated with histopathological workup. CT thrombus detection sensitivity and specificity for both readers was 0.93 and 0.8 respectively. MRI sensitivity and specificity for both readers was 1.0/0.85 and 0.75.Readers I and II evaluated the uppermost extension of the cranial tumor thrombus by both CT and MRI. CT and MR accuracy was 78% and 72%, 88% and 76% respectively. CONCLUSION: In cases of a suspected tumor thrombus, MRI and multidetector CT imaging showed similar staging results. Consequently, these staging modalities can be used to assess the extension of the tumor thrombus.     

High-resolution MRI of the triangular fibrocartilage complex (TFCC) at 3T: comparison of surface coil and volume coil

PURPOSE: To evaluate high-resolution MRI of the triangular fibrocartilage complex (TFCC) at 3T using a surface coil (SC) or volume coil (VC). MATERIALS AND METHODS: MRI was obtained from nine volunteers in the supine position with a 3-inch SC and in prone position with a transmit-receiver wrist VC at 3 T. Coronal two-dimensional-gradient echo (2D-GRE) images (TR/TE/FA = 500 msec/15 msec/40 degrees , 1 mm slice-thickness, 60 mm field of view [FOV], 192 x 256 matrix) and coronal 3D-GRE images (TR/TE/FA = 33 msec/15 msec/10 degrees , 0.8 mm slice-thickness, 80 mm FOV, 256 x 256 matrix) were used. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) of the TFCC and surrounding structures were measured. For qualitative measurement, visualization of TFCC and intercarpal ligaments was graded. RESULTS: SNR of TFCC, cartilage, and bone marrow on 2D-GRE with SC/VC was as follows: 5.3/5.3 (TFCC), 16.5/14.4 (cartilage), and 3.61/3.96 (bone marrow). 3D-GRE showed similar SNR. Cartilage-TFCC/cartilage-bone marrow CNR were 11.1/12.8 (SC-2D-GRE), 8.8/10.5 (VC-2D-GRE), 14.1/15.5 (SC-3D-GRE), and 11.9/15.0 (VC-3D-GRE). Quantitative values were not significantly different between SC and VC. Visualization of TFCC and intercarpal ligament with SC was superior to that with VC. All structures show higher scores with 3D-GRE imaging compared to 2D-GRE imaging. CONCLUSION: SC may provide superior qualitative and quantitative results and can be an alternative in case of difficulty in prone position at 3T.     

MRI in staging of lung cancer

PURPOSE: Overview of magnetic resonance imaging (MRI) in staging of lung cancer. MATERIAL AND METHODS: Currently available methods of imaging lung cancer, lymph node and distant metastases by MRI are explained. At present, MRI is mainly used in the detection of cerebral metastases and assessment of infiltration of the thoracic wall and of the mediastinum. The capabilities of T2-weighted single-shot TSE (HASTE) and T1-weighted 3D gradient echo techniques (VIBE) are demonstrated. RESULTS: With the advent of new fast sequences like HASTE and VIBE the spatial resolution comes close to that of computed tomography but with an outstanding soft tissue contrast and without radiation exposure. The introduction of lymph node specific contrast media will improve sensitivity and specificity in N staging. Additionally, whole-body MRI is capable of detecting distant metastases, in particular in the organs at risk, i.e. brain, upper abdomen and musculoskeletal system. CONCLUSION: MRI is gaining importance as part of a multimodal imaging approach for staging of lung cancer.     

磁共振VIBE增强扫描联合冠状位T2WI诊断肝外远端胆管癌

目的探讨MR三维容积内插体部检查(volume interpolated body examination,VIBE)增强联合冠状位T2WI诊断肝外远端胆管癌的价值。方法 17例经手术病理证实的肝外远端胆管癌行MR冠状位T2WI、VIBE增强扫描,观察病灶的MR表现,测量病灶长度。结果 17例肝外远端胆管癌在冠状位T2WI上表现为肝外远端胆管梗阻,10例于胆管梗阻处见软组织肿块、3例见胆管壁增厚,同周围组织相比呈低信号。VIBE动态增强扫描17例病灶均呈进行性强化,10例肿块者中2例均匀性强化,8例肿块边缘强化更明显;7例胆管壁增厚、强化,在轴位VIBE图像上呈"环"形强化,在冠状位VIBE图像上,5例呈平行的"线条"状强化,2例呈"V"形强化。病灶平均长度为18.7 mm。结论 VIBE增强联合冠状位T2WI能较好地显示肝外远端胆管癌。     

T1 mapping联合常规MRI扫描方案评估膝关节软骨损伤

目的评估在常规MRI扫描方案中加入T1 mapping成像能否提高对膝关节软骨损伤的诊断效能。方法选取86例患者的88个膝关节接受了膝关节MRI检查和关节镜检查。MRI检查采用常规方案并加入T1 mapping成像。术前2位影像科医师对所有MRI检查图像进行一致的诊断,评估是否存在软骨损伤并进行软骨损伤MRI分级,首先评估常规MRI扫描方案的图像,然后评估T1 mapping联合常规MRI扫描方案的图像。由1位骨科医师在关节镜下进行软骨损伤关节镜分级并作为金标准。计算两种MRI扫描方案评估软骨损伤的敏感度和特异度,统计分析两种扫描方案的诊断结果是否存在差异。结果关节镜检出的256个软骨损伤,常规MRI扫描方案的敏感度、特异度分别为59.0%和98.6%,T1 mapping联合常规MRI扫描方案的敏感度、特异度分别为85.9%和93.2%。T1 mapping联合常规MRI扫描方案显著提高了MRI扫描诊断早期关节软骨损伤的敏感度,关节镜1级软骨损伤的敏感度从18.6%提高至71.2%,关节镜2A级软骨损伤的敏感度从74.3%提高至94.3%。上述两种扫描方案的结果差异均有统计学意义(P<0.05)。结论常规MRI扫描方案中加入T1 mapping成像,可提高对膝关节软骨损伤的敏感度,为临床诊断早期膝关节软骨损伤提供影像学依据。     

Quantitative assessment of patellar cartilage volume and thickness at 3.0 tesla comparing a 3D-fast low angle shot versus a 3D-true fast imaging with steady-state precession sequence for reproducibility

OBJECTIVES: We sought to compare patellar cartilage volume and thickness measurement between 3D-FLASH and 3D-True fast imaging with steady-state precession (FISP) image data at 3.0 T. MATERIALS AND METHODS: One knee each of 6 healthy adults was examined by axial magnetic resonance imaging (MRI) performed with a 3D-fast flow angle shot (FLASH) water-excitation sequence and a 3D-TrueFISP water-excitation sequence (spatial resolution 0.31 x 0.31 x 1.5 mm3). Patellar cartilage volume and mean/maximum thickness were calculated. Intraindividual/average reproducibility and interindividual variability were determined from 3 consecutive data sets acquired for each volunteer and sequence. RESULTS: Patellar cartilage volume and thickness as well as reproducibility was slightly but not significantly lower for the 3D-TrueFISP data than for the 3D-FLASH data (volume: 3.4-6.3 mL (3D-FLASH)/3.1-6.0 mL (3D-TrueFISP), average reproducibility 1.8% (3D-FLASH)/4.4% (3D-TrueFISP); mean thickness: 2.1-2.8 mm (3D-FLASH)/1.9-2.6 mm (3D-TrueFISP), average reproducibility 2.8% (3D-FLASH)/3.8% (3D-TrueFISP); maximum thickness: 4.7-6.6 mm (3D-FLASH)/4.5-6.2 mm (3D-TrueFISP), average reproducibility 2.6% (3D-FLASH)/4.1% (3D-TrueFISP)). Interindividual variability was comparable for both sequence techniques. CONCLUSION: At 3.0 T, the 3D-FLASH sequence showed tendency to be slightly superior to the 3D-TrueFISP sequence considering robust and valid assessment of quantitative cartilage parameters in young healthy adults, although there was found no significant statistical difference between both imaging techniques. However, in patients suffering from osteoarthritis (OA), the 3D-TrueFISP sequence might prove advantageous for monitoring of disease progression and evaluation of therapy success, particularly because the substantially higher signal to noise ratio/contrast to noise ratio values might allow for higher spatial resolution and hence for improvement of the accuracy of segmentation process especially at the articular surface.     

3D -FLASH序列动态MR增强扫描技术在乳腺疾病中的应用

目的 探讨3D-FLASH动态增强扫描在乳腺疾病检查中的应用价值. 方法 将108例经病理证实的乳腺疾病患者作为研究对象,均为女性,年龄35～76岁,平均47岁,使用Siemens 1.0T超导磁共振扫描仪和双环极阵列乳腺线圈.均先常规平扫,静脉注射造影剂Gd-DTPA(0.1 mmol/kg体重)后,三维-快速小角度激发(3D-FLASH)序列获得双侧乳腺轴位动态增强图像并进行减影. 结果 108例中,良性病变62例,乳腺癌46例,术前MRI诊断符合率81.5%. 结论 3D-FLASH序列动态增强是乳腺病变中最有价值的检查序列.     

MRT zum Staging des Lungenkarzinoms

Purpose

Overview of magnetic resonance imaging (MRI) in staging of lung cancer.

Material and methods

Currently available methods of imaging lung cancer, lymph node and distant metastases by MRI are explained. At present, MRI is mainly used in the detection of cerebral metastases and assessment of infiltration of the thoracic wall and of the mediastinum. The capabilities of T2-weighted single-shot TSE (HASTE) and T1-weighted 3D gradient echo techniques (VIBE) are demonstrated.

Results

With the advent of new fast sequences like HASTE and VIBE the spatial resolution comes close to that of computed tomography but with an outstanding soft tissue contrast and without radiation exposure. The introduction of lymph node specific contrast media will improve sensitivity and specificity in N staging. Additionally, whole-body MRI is capable of detecting distant metastases, in particular in the organs at risk, i.e. brain, upper abdomen and musculoskeletal system.

Conclusion

MRI is gaining importance as part of a multimodal imaging approach for staging of lung cancer.     

Three-dimensional gradient echo versus spin echo sequence in contrast-enhanced imaging of the pituitary gland at 3 T

Introduction

To clarify whether a three-dimensional-gradient echo (3D-GRE) or spin echo (SE) sequence is more useful for evaluating sellar lesions on contrast-enhanced T1-weighted MR imaging at 3.0 Tesla (T).

Methods

We retrospectively assessed contrast-enhanced T1-weighted images using 3D-GRE and SE sequences at 3.0 T obtained from 33 consecutive patients with clinically suspected sellar lesions. Two experienced neuroradiologists evaluated the images qualitatively in terms of the following criteria: boundary edge of the cavernous sinus and pituitary gland, border of sellar lesions, delineation of the optic nerve and cranial nerves within the cavernous sinus, susceptibility and flow artifacts, and overall image quality.

Results

At 3.0 T, 3D-GRE provided significantly better images than the SE sequence in terms of the border of sellar lesions, delineation of cranial nerves, and overall image quality; there was no significant difference regarding the boundary edge of the cavernous sinus and pituitary gland. In addition, the 3D-GRE sequence showed fewer pulsation artifacts but more susceptibility artifacts.

Conclusion

Our results indicate that 3D-GRE is the more suitable sequence for evaluating sellar lesions on contrast-enhanced T1-weighted imaging at 3.0 T.     

Lung MRI at 1.5 and 3 Tesla: observer preference study and lesion contrast using five different pulse sequences

OBJECTIVES: To compare the image quality and lesion contrast of lung MRI using 5 different pulse sequences at 1.5 T and 3 T. MATERIALS AND METHODS: Lung MRI was performed at 1.5 T and 3 T using 5 pulse sequences which have been previously proposed for lung MRI: 3D volumetric interpolated breath-hold examination (VIBE), true fast imaging with steady-state precession (TrueFISP), half-Fourier single-shot turbo spin-echo (HASTE), short tau inversion recovery (STIR), T2-weighted turbo spin-echo (TSE). In addition to 4 healthy volunteers, 5 porcine lungs were examined in a dedicated chest phantom. Lung pathology (nodules and infiltrates) was simulated in the phantom by intrapulmonary and intrabronchial injections of agarose. CT was performed in the phantom for correlation. Image quality of the sequences was ranked in a side-by-side comparison by 3 blinded radiologists regarding the delineation of pulmonary and mediastinal anatomy, conspicuity of pulmonary nodules and infiltrates, and presence of artifacts. The contrast of nodules and infiltrates (CNODULES and CINFILTRATES) defined by the ratio of the signal intensities of the lesion and adjacent normal lung parenchyma was determined. RESULTS: There were no relevant differences regarding the preference for the individual sequences between both field strengths. TSE was the preferred sequence for the visualization of the mediastinum at both field strengths. For the visualization of lung parenchyma the observers preferred TrueFISP in volunteers and TSE in the phantom studies. At both field strengths VIBE achieved the best rating for the depiction of nodules, whereas HASTE was rated best for the delineation of infiltrates. TrueFISP had the fewest artifacts in volunteers, whereas STIR showed the fewest artifacts in the phantom. For all but the TrueFISP sequence the lesion contrast increased from 1.5 T to 3 T. At both field strengths VIBE showed the highest CNODULES (6.6 and 7.1) and HASTE the highest CINFILTRATES (6.1 and 6.3). CONCLUSION: The imaging characteristics of different pulse sequences used for lung MRI do not substantially differ between 1.5 T and 3 T. A higher lesion contrast can be expected at 3 T.     

HASTE序列在老年人腹部磁共振检查中的应用

目的探讨半傅立叶采集单次激发快速自旋回波序列（HASTE）在老年人腹部磁共振检查中的应用价值。方法搜集我院2013年7月～2014年2月行腹部磁共振检查的老年患者40例,扫描序列包括：呼吸门控横轴位TSE-T2WI、冠状位及横轴位HASTE、横轴位T1WI化学位移成像、横轴位平扫VIBE序列,比较各序列在老年人腹部检查中的应用价值。结果HASTE序列成像速度快,不受呼吸频率、屏气效果的限制,图像质量最佳。结论 HASTE序列在老年人腹部磁共振检查中有较高的应用价值。     

水激发三维VIBE肩关节MR造影对Bankart病变的评价

目的评价肩关节MR造影水激发三维容积内插梯度回波(volumetric interpolated breath-hold examination,VIBE)序列对Bankart病变的诊断价值。资料与方法由2名影像诊断医师独立回顾99例肩关节MR造影常规序列和三维VIBE重建图像,判定有无Bankart病变以及骨性Bankart病变,计算其敏感性和特异性。采用McNemar检验评价常规序列与三维VIBE的诊断价值差异是否存在统计学意义。结果 99例患者中,关节镜证实前下方盂唇完整41例,Bankart病变58例,其中26例为骨性Bankart病变。三维VIBE对Bankart病变的敏感性、特异性分别为91.38%～93.10%和95.12%～97.56%;对骨性Bankart病变分别为96.15%和95.89%～97.26%。常规序列对Bankart病变的敏感性、特异性分别为91.38%～96.55%和97.56%;对骨性Bankart病变分别为42.31%～50%和97.26%～100%。三维VIBE和常规序列对于Bankart病变的诊断性能差异无统计学意义,但前者判断骨性Ban-kart病变的敏感性显著优于后者。结论在肩关节MR造影中,水激发三维VIBE序列可全面评价Bankart病变。     

Wrist and finger joint MR imaging in rheumatoid arthritis.

PURPOSE: To elaborate the best MR imaging protocol for studies in rheumatoid arthritis (RA) and to evaluate the sensitivity and interobserver agreement with respect to detection of bone erosions (MR and radiography) and grading of synovial membrane hypertrophy (MR imaging only). MATERIAL AND METHODS: MR imaging and conventional radiography of wrist and metacarpophalangeal (MCP) joints were performed in 41 RA patients and 3 healthy controls. The following pulse sequences were applied: T1-weighted spin-echo (T1-SE) with and without contrast enhancement, T2-SE, T2-turbo-SE, T1-2D-FLASH, T1-3D-FLASH, fat-saturated-T1-SE, STIR and 3D-DESS. RESULTS: Bone erosions were found by MR compared to radiography in 261 versus 85 bones of the wrist (ratio 3.1) and 59 versus 21 MCP joint quadrants (ratio 2.81). MR and radiography interobserver agreements were both approximately 90%. Likewise, MR scored synovial membrane hypertrophy in wrist and MCP joints with a high interobserver agreement. The most informative MR sequence appeared to be contrast-enhanced T1-SE MR, preferably with fat saturation. A STIR sequence or T2-weighted fat saturation sequence was useful in screening for joint disease. CONCLUSION: The sensitivity of MR is superior to conventional radiography with respect to detection of bone erosions in wrist and MCP joints. The interobserver agreement for MR and radiography was similar. Thus, MR of wrist and finger joints may become a useful supplement to conventional radiography in the evaluation of RA patients in clinical trials and clinical practice.     

Diagnostic Accuracy of Screening MR Imaging Using Unenhanced Axial CISS and Coronal T2WI for Detection of Small Internal Auditory Canal Lesions

BACKGROUND AND PURPOSE:While enhanced T1WI is considered the “gold standard” for detection of internal auditory canal pathology, unenhanced fluid-sensitive sequences have shown high sensitivity for lesion identification. Our purpose was to evaluate the diagnostic accuracy of an unenhanced MR imaging protocol using axial CISS and coronal T2WI for detection of small (10 mm or less) internal auditory canal lesions.MATERIALS AND METHODS:Twenty-three patients with small internal auditory canal lesions and 13 patients without lesions who had undergone MR imaging using the screening protocol and confirmatory gadolinium-enhanced thin section T1WI were identified. Two blinded neuroradiologists retrospectively evaluated all examinations using 1) only axial CISS, 2) only coronal T2WI, and 3) axial and coronal sequences together. Accuracy, specificity, sensitivity, and interobserver agreement were assessed.RESULTS:Median maximum lesion dimension was 4 mm (range, 2–10 mm). Accuracy, specificity, and sensitivity for axial CISS alone were 0.94, 0.96, and 0.91 for observer 1 and 0.94, 0.92, and 1.00 for observer 2. The data for the coronal T2WI sequence only were 0.94, 0.96, and 0.91 for observer 1, and 0.99, 1.00, and 0.96 for observer 2. Using axial and coronal sequences, the data were 0.97, 0.96, and 1.00 for observer 1, and 0.99, 0.98, and 1.00 for observer 2. κ coefficients were 0.84 for the axial sequence only, 0.90 for coronal only, and 0.91 for axial and coronal both.CONCLUSIONS:Screening noncontrast MR imaging using a combination of axial CISS and coronal T2WI sequences can detect small internal auditory canal lesions with 100% sensitivity and excellent interobserver agreement.

Vestibular schwannoma is the most common lesion diagnosed during MR imaging evaluation of unilateral sensorineural hearing loss.^1,2 Nevertheless, only 2.7%–4.7% of contrast-enhanced MRIs performed for audiovestibular symptoms will diagnose vestibular schwannomas.^3,4 Although gadolinium-enhanced thin section MR imaging has historically been considered the “gold standard” for detection of internal auditory canal (IAC) tumors such as vestibular schwannomas, lower cost unenhanced, fluid-sensitive sequences have demonstrated pooled sensitivities ranging from 96% to 98% for detection of IAC lesions ranging from 2 mm to >20 mm in diameter.⁵ In the era of rising health care costs, especially for diagnostic imaging, the cost savings associated with a low-cost screening IAC MR imaging may become an important factor in decision-making.At our institution, we have performed screening MR imaging of the IACs since the 1990s using fluid-sensitive axial and coronal sequences. In 1996, Allen et al⁶ demonstrated 98% accuracy of an axial and coronal T2-weighted IAC screening MR imaging protocol in 25 patients whose lesions had a mean diameter of 12 mm. Two lesions measuring <5 mm were missed. In 2006, the axial T2 FSE sequence at our institution was replaced by an axial dual-excitation balanced steady-state interference sequence termed CISS (Siemens, Erlangen, Germany), as 3D CISS had been reported to have twice the contrast-to-noise ratio compared with 3D T2WI.⁷ As no study has evaluated the accuracy of a 2-plane screening IAC MR imaging protocol using CISS for detection of small (≤10 mm) lesions, we chose to evaluate the diagnostic accuracy of a 2-sequence screening MR imaging protocol using unenhanced axial CISS and coronal T2WI for detection of small IAC lesions.