Quality comparison between three-dimensional T2-weighted SPACE and two-dimensional T2-weighted turbo spin echo magnetic resonance images for the brachytherapy planning evaluation of prostate and periprostatic anatomy

PurposeThe purpose of this study was to compare an isotropic three-dimensional (3D) T2-weighted sequence sampling perfection with application-optimized contrasts by using flip angle evolution (SPACE) with an axial two-dimensional T2-weighted turbo spin echo (TSE) sequence with regard to overall image quality and the delineation of normal prostate and periprostatic anatomy for low-dose-rate prostate cancer brachytherapy planning evaluation.Methods and MaterialsPatients (n = 69) with prostate cancer who had pelvic magnetic resonance imaging (MRI) for low-dose-rate brachytherapy treatment planning were included. Three radiologists independently assessed the visibility of nine anatomic structures on each sequence by using a 5-point scale and overall image quality by using a 4-point scale. The significance of the differences in diagnostic performance was tested with a Wilcoxon signed rank test.ResultsNo significant intersequence differences were found for most (7/9) anatomical structures and overall image quality. The mean scores for visibility of anatomical structures on the 3D SPACE and 2D TSE sequences, respectively, were as follows: the zonal anatomy (3.7; 3.9, p = 0.05), prostate capsule (3.9; 4.0, p = 0.08), neurovascular bundle (2.9; 2.9, p = 0.9), rectoprostatic angle (3.8; 3.8, p = 0.35), rectum (4.2; 4.3, p = 0.26), urethra (3.8; 3.9, p = 0.12), urinary bladder (4.6; 4.6, p = 0.61), and overall image quality (2.9; 2.9, p = 0.33). 3D SPACE was superior for delineation of the genitourinary diaphragm (3.8; 3.6, p = 0.003), whereas 2D TSE was superior for delineation of the seminal vesicles (3.5; 4.0, p < 0.0001).ConclusionsAnatomic delineation of the prostatic and periprostatic anatomy provided by the 3D SPACE sequence is as robust in quality as that provided by a conventional 2D TSE sequence with superior delineation of the genitourinary diaphragm. For MRI-based brachytherapy treatment planning, the 3D SPACE sequence with subcentimeter isotropic resolution can replace the 2D TSE sequence and be incorporated into standard MRI protocols.     

Evaluation of turbo spin echo sequences for MRI of focal liver lesions at 0.5 T

To determine whether turbo spin echo (TSE) sequences can replace conventional T2-weighted spin echo (SE) sequences in MRI of the liver, 40 patients with focal liver lesions were imaged at 0.5 T. A T2-weighted SE sequences (TR/TE 1800/90 ms, number of signals averaged [NEX]=2, scan time=7:16 min), a TSE sequence (TR/TE 1800/90 ms, NEX=4, number of echos per excitation=13, echo spacing=12.9 ms, scan time=4:16 min) and a T1-weighted SE sequence (TR/TE 350/15 ms, NEX=2, scan time=4:21 min) were obtained and image quality, lesion detectability and lesion differentiation were evaluated qualitatively by subjective assessment using scores and quantitatively by lesion-liver contrast-to-noise (CNR) and tumour/liver signal intensity (SI) ratios. The image quality of the TSE sequence was substantially better compared with the T2-weighted SE sequence due to a reduction in motion artefacts and better delineation of anatomical details. Of a total of 158 visible lesions the T1-weighted SE, TSE, and T2-weighted SE sequences showed 91%, 81% and 65% of the lesions, respectively. Thus the TSE sequence depicted 24% (P< 0.001) more lesions than the T2-weighted SE sequence. In all types of pathology the lesion-liver CNR of the TSE sequence was significantly (P< 0.001) higher compared to the CNR of the T2-weighted SE sequence (+ 55–65%), indicating superior lesion conspicuity. Lesion characterization was equally good on the two T2-weighted sequences with no difference in the tumour/liver SI ratio. Using a criterion of tumour/liver SI ratio equal to or higher than 2, haemangiomas larger than 1 cm in diameter could be differentiated from other lesions with a sensitivity and specificity of 95% and 96%, respectively. Our results indicate that the TSE sequence is suitable for replacing the conventional T2-weighted SE sequence in MRI of focal liver lesions.This paper was presented at ECR 1993 Correspondence to: B. Kreft     

Distortion-corrected T2 weighted MRI: a novel approach to prostate radiotherapy planning

The purpose of this study was to evaluate distortion-corrected MRI as a radiotherapy planning tool for prostate cancer and the resultant implications for dose sparing of organs at risk. 11 men who were to be treated with radical conformal radiotherapy for localized prostate cancer had an MRI scan under radiotherapy planning conditions, which was corrected for geometric distortion. Radiotherapy plans were created for planning target volumes derived from the MRI- and CT-defined prostate. Dose volume histograms were produced for the rectum, bladder and penile bulb. The mean volume of the prostate as defined on CT and MRI was 41 cm3 and 36 cm3, respectively (p = 0.009). The predicted percentage of the rectum treated to dose levels of 45-65 Gy was significantly lower for plans delineating the prostate with MRI than for those with CT. The rectal-sparing effect was confined to the lowermost 4 cm of the rectum (anal canal). There were no differences between the predicted doses to bladder or penile bulb (as defined using MRI) between plans. In conclusion, prostate radiotherapy planning based on distortion-corrected MRI is feasible and results in a smaller target volume than does CT. This leads to a lower predicted proportion of the rectum, in particular the lower rectum (anal canal), treated to a given dose than with CT.     

The value of T2*-weighted gradient-echo MRI for the diagnosis of cerebral venous sinus thrombosis

ObjectivesThe purpose of this study is to compare the various magnetic resonance imaging (MRI) sequences when they are used to visualize and evaluate cerebral venous thrombosis.MethodsEleven patients with cerebral venous thrombosis were retrospectively analyzed using computed tomography, MRI, magnetic resonance angiography (MRA), and conventional angiography. The MR sequence included T1-weighted spin echo (SE) imaging, obtained before and after administration of contrast medium, T2-weighted turbo spin echo (TSE), fluid-attenuated inversion recovery (FLAIR), T2*-weighted conventional gradient-echo (GRE), as well as three-dimensional (3D) venous time-of-flight MRA and conventional angiography.ResultsIn all of our patients, the venous sinus thromboses were most successfully detected during the T2*-weighted GRE sequence. The thrombosis was well visualized with the T1-weighted SE sequence in three of four patients in whom it was in the subacute stage. The T2*-weighted GRE sequence was superior to the T2-weighted TSE, T1-weighted SE, and FLAIR sequences in all patients. Enhanced 3D MR venography showed the thrombosed segment of the venous sinus and well correlated with the conventional angiographic findings.ConclusionsThe T2*-weighted conventional GRE sequences may be the best method for detecting of cerebral venous thrombosis. Therefore, it would seem to be beneficial to integrate a T2*-weighted conventional GRE sequence into the MR protocol to diagnose cerebral venous thrombosis.     

Magnetic resonance (MR) imaging of prostatic tumours, a comparison with X-ray CT and transrectal sonography (TRS)

A total of 7 healthy volunteers and 31 patients have been examined clinically, by MRI, TRS, and biopsy. In those patients with established carcinoma, a CT examination was also performed. For the MRI study, a superconducting MR 2000 imager (Picker International) operated at 0.15 T was used with multiplanar SE and IR sequences. SE sequences with long echo times detected prostatitis, adenoma and carcinoma of the prostate with a high degree of sensitivity. However, at present, differentiation between adenoma, prostatitis and carcinoma is not possible with sufficient accuracy. In these studies we were unable to establish a correlation between the signal pattern and staging and/or grading of the carcinoma. Reliable diagnosis of a prostate carcinoma still requires a biopsy. Because of the high soft tissue contrast and the possibility of selecting any orientation for the plane under investigation, however, MRI represents an improvement in the preoperative diagnosis of local spread.     

Phased array breath-hold versus non-breath-hold MR imaging of focal liver lesions: A prospective comparative study

This study was undertaken to determine whether phased array breath-hold T1- and T2-weighted sequences can replace non-breath-hold spin echo (SE) sequences in the imaging of focal liver lesions by comparing overall image quality, liver-lesion contrast, and artifact. Both breath-hold and non-breath-hold T1-weighted and T2-weighted imagings of focal liver lesions were prospectively compared in 120 patients with suspected focal liver lesions imaged at 1.5 T with use of a body phased array multicoil. Breath-hold images were acquired with T1-weighted fast low-angle shot (FLASH) and T2-weighted turbo spin echo (TSE) sequences, and non-breath-hold images were made with conventional T1- and T2-weighted SE sequences. Qualitative image analysis was done by three blinded readers, and quantitative analysis was done. The highest signal-to-noise ratios were obtained with breath-hold T1-weighted FLASH sequence. The signal-to-noise ratios of breath-hold T2-weighted TSE sequence were slightly inferior to those of non-breath-hold SE sequence. Both T1-weighted and T2-weighted breath-hold sequences had less image artifact. Overall image quality of breath-hold sequences was better than that of non-breath-hold sequences for both T1- and T2-weighted sequences (P < .01). The tissue contrast of T1-weighted FLASH sequence was superior to that of SE sequence (P < .01). On T2-weighted imaging, tissue contrast of solid lesions was better on conventional SE sequence than that on breath-hold TSE sequence (P < .01). Respiratory ghost artifact was less prominent on T1-weighted FLASH sequence, although this artifact was occasionally seen on breath-hold T2-weighted TSE sequence. In a state-of-art MR unit with use of a phased array multicoil, conventional T1-weighted can be replaced by breath-hold sequences. On T2-weighted imaging, because solid tumor-liver contrast on breath-hold TSE imaging is inferior to that on non-breath-hold SE image, breath-hold imaging may not replace conventional non-breath-hold T2-weighted SE sequence.     

Fast and ultrafast magnetic resonance imaging in renal lesions

Our purpose was to analyze and compare the image quality and contrast-to-noise ratio (CNR) of different fast T1- and T2-weighted sequences with conventional spin-echo sequences in renal MRI. Twenty-three patients with focal renal lesions were examined with a T2-weighted ultrafast turbo spin-echo (UTSE) sequence with and without frequency selective fat suppression (SPIR), a combined gradient-and-spin-echo sequence (GraSE), and a conventional spin-echo sequence (SE). In addition, T1-weighted images were obtained pre-and postcontrast, using a fast spin-echo sequence (TSE) with and without SPIR and the conventional SE sequence. Among the T2-weighted images, the highest CNR and the best image quality were obtained with the UTSE sequence, followed by the fat-suppressed UTSE sequence. GraSE and conventional SE sequences showed a significantly lower CNR and image quality (p < 0.05). The T1-weighted sequences did not show significant differences, in either precontrast or postcontrast measurements. T2-weighted UTSE with and without fat suppression combined excellent image quality and high CNR for imaging and detection of renal lesions. The T1-weighted fast sequences provided no alternative to the gradient-echo or to the conventional SE sequences. The results of this systematic study suggest the use of T2-weighted fast techniques for improved diagnostic accuracy of renal MRI.     

垂体卒中的MRI诊断与手术、病理对照研究（附52例分析）

目的探讨垂体卒中的MRI不同表现及鉴别诊断.材料和方法对52例垂体卒中患者行常规TSE序列/Gd-DT-PA MRI增强扫描、CT扫描,并与手术和病理结果进行对照.结果94.2%的垂体卒中发生于垂体巨大腺瘤或大腺瘤,65.4%的病例MRI表现为T1高信号或等、高混杂信号,T2高信号或等、高混杂信号,MRI诊断垂体卒中准确率达100%.结论MRI对于垂体卒中的诊断价值优于CT,MRI平扫即能明确诊断.     

Detection of parametrial invasion in cervical carcinoma: role of short tau inversion recovery sequence

AIM: To investigate the role of short tau inversion recovery (STIR) sequence in the detection of parametrial invasion in patients with carcinoma of the cervix. MATERIALS AND METHODS: Axial magnetic resonance imaging (MRI) images of the cervical region using T1 weighted turbo spin echo (TSE), TSE T2, STIR and T1 weighted dynamic gadolinium enhanced SE sequences were obtained in 38 patients with cervical carcinoma. All the images were assessed for the presence or absence of parametrial invasion using a standard scoring system. The diagnostic confidence, image quality, sensitivity, specificity, positive and negative predictive values and accuracy of each sequence were compared. RESULTS: The sensitivity, specificity, positive predictive value, negative predictive value and accuracy for each sequence in the diagnosis of parametrial invasion were: 60%, 80%, 32%, 93% and 78% for unenhanced T1W sequence; 90%, 92%, 64%, 98% and 92% for TSE T2 sequence; 90%, 94%, 69%, 98% and 93% for STIR sequence; and 90%, 80%, 41%, 98% and 82% for dynamic T1W sequence, respectively. Image quality and diagnostic confidence were both better for STIR and T2 compared to the dynamic T1 sequence. CONCLUSION: Dynamic T1W imaging is inferior to STIR and TSE T2 sequences. STIR is of similar value in the detection of parametrial invasion in cervical carcinoma as a TSE T2W sequence; their simultaneous use is not justified.     

脂肪肝内正常肝岛及正常肝内局灶脂肪变性的CT与MR诊断

目的：探讨脂肪肝内正常肝岛及正常肝内局灶脂肪变性的ＣＴ与ＭＲ征象。方法：６例脂肪肝内正常肝组织岛（Ａ组）与７例正常肝内局灶性脂肪变性（Ｂ组）病人,ＣＴ与常规ＳＥＴ１ 及Ｔ２ 加权及梯度回波Ｔ１ 加权ｉｎ－ ｐｈａｓｅ及ｏｕｔ－ ｐｈａｓｅ ＭＲ成像。结果：增强前、后ＣＴ显示正常肝组织岛保持正常肝组织与脾脏密度关系;肝组织局灶脂肪变性呈相对低密度。ＭＲＩＳＥＴ１、Ｔ２ 加权成像及梯度回波ｉｎ－ ｐｈａｓｅＴ１ 加权成像显示正常肝组织岛相对低信号区;局灶脂肪变性区呈稍高信号。梯度回波ｏｕｔ－ ｐｈａｓｅ Ｔ１ 加权成像正常肝组织岛呈高信号;局灶脂肪变性区呈低信号。脂肪抑制Ｔ２ 加权成像均呈等信号。结论：采用ＭＲ的梯度回波ｏｕｔ－ ｐｈａｓｅＴ１ 加权及ＴＳＥＴ２ 加权脂肪抑制成像可以诊断正常肝岛及正常肝内的局灶脂肪变性。     

MRI在TMJ损伤中诊断价值研究

目的　研究MRI对观察损伤性颞颌关节结构的诊断价值。方法　对山羊颞颌关节损伤分别于 3h、7d及 1月行MRI检查 ,采用斜矢状闭、开口位梯度回波T1W / 3D/WATS、自旋回波PDW /TSE、T1W /SE和T2 W /TSE序列及冠状闭口位T1W / 3D/WATS、PDW /TSE扫描观察TMJ结构变化 ,并进行组织学观察。结果　MRI观察到TMJ损伤早期髁状突表面软骨碎裂 ,关节盘挫裂和移位 ,关节间隙减小及关节腔内有出血 ,损伤后期可见髁状突表面软骨破坏 ,关节盘畸形 ,关节间隙减小。结论　MRI能全面地观察TMJ损伤后骨性结构及附件结构和形态的变化 ,对颞颌关节损伤的诊治有重要价值     

High-resolution MRI of pancreatic masses with a new circularly polarized body phased-array coil

A total of 18 patients with clinical suspicion of a pancreatic tumor underwent dynamic contrast-enhanced CT and MRI examinations. A fat-suppressed T1-weighted 2D fast-low-angle-shot (FLASH) sequence and a T2-weighted spin-echo (SE) sequence were applied in a transverse orientation using a circularly polarized (CP) body phased-array coil. The FLASH sequence was repeated after Gd-DTPA administration. The highest spatial resolution was 1.37×1.37×3.00 mm³. In two cases a half Fourier single-shot turbo-SE sequence (HASTE) was additionally applied. In a comparison between CT and MRI, pancreatic masses could be demonstrated and characterized with excellent image quality. The fat-saturated 2D FLASH sequence yielded the highest contrast-to-noise ratios after Gd-DTPA administration between pancreas and inflammatory or neoplastic lesion. One non-contour deforming carcinoma could be detected only with MRI and was only retrospectively visible on CT with an element of uncertainty. Magnetic resonance imaging using a CP body phased-array coil and fat-suppressed T1- and T2-weighted FLASH, SE, and turbo-SE sequences offers diagnostic possibilities in improved imaging of the pancreas.     

True proton density and T2-weighted turbo spin-echo sequences for routine MRI of the brain

Our aim was to evaluate the diagnostic reliability of turbo spin-echo (TSE) sequences compared to a conventional dual-echo spin-echo (SE) sequence in routine brain MRI at 1.0 T. The following demands were made on TSE sequences: acquisition time-reduction of at least 50% and true proton density (PD) contrast (lowsignal cerebrospinal fluid). A conventional spin-echo and two single-echo TSE sequences were used in 150 patients, a dual-echo TSE sequence in addition in 50 patients. Demonstration of most anatomical structures and disorders was equivalent with TSE and SE sequences. Advantages of TSE were reduced flow artefacts on T2-weighted images, better lesion contrast on PD-weighted TSE images (especially in the dual-echosequence) and acquisition time reduction to about 5 min (single-echo TSE) and 335 min (dual-echo TSE). Disadvantages of TSE were: reduced contrast of tron-containing substances such as heamosiderin and of areas of calcification. By virtue of the shorter acquisition time and diagnostic reliability dual-echo TSE proved the best sequence. If it is used with only one acquisition-whereby image quality but not diagnostic reliability is slightly decreased — acquisition time can be further reduced to 148 min. Application of a susceptibility-sensitive gradient-echo sequence, such as FLASH, compensates for the disadvantages mentioned above.     

Breath-hold MR imaging of focal liver lesions: comparison of fast and ultrafast techniques

The performance of breath-hold MR imaging using two T2-weighted hybrid sequences (TSE, TGSE), two T2-weighted single-shot sequences (HASTE, EPI-SE), and one T1-weighted gradientecho sequence (FLASH) was compared with a standard conventional T2-weighted SE sequence in 20 patients with focal liver lesions. Liver signal-to-noise ratio was highest spleen-liver contrast-to-noise ratio (54.3 ± 8.3) and thee HASTE (41.1 ± 12.5) sequence, whereas the highest spleen-liver contrast-noise-ratio was obtained by the TSE sequence (38.9 ± 20.7). Lesion-liver CNR was highest with the TSE sequence (63.9 ± 21.4). With both TSE and HASTE significantly (p < 0.01) more lesions were detected as compared with SE and EPE-SE sequences. Our results indicate that breath-hold TSE and HASTE sequences will eventually replace conventional T2-weighted SE techniques due to their insensitivity to motion artifacts, superior lesion detectability and inherently short acquisitions times.Correspondence to: J. Gaa     

Fast T2*-weighted MRI of the prostate at 3 Tesla

Purpose:

To describe a rapid T2*‐weighted (T2*W), three‐dimensional (3D) echo planar imaging (EPI) sequence and its application in mapping local magnetic susceptibility variations in 3 Tesla (T) prostate MRI. To compare the sensitivity of T2*W EPI with routinely used T1‐weighted turbo‐spin echo sequence (T1W TSE) in detecting hemorrhage and the implications on sequences sensitive to field inhomogeneities such as MR spectroscopy (MRS).

Materials and Methods:

B₀ susceptibility weighted mapping was performed using a 3D EPI sequence featuring a 2D spatial excitation pulse with gradients of spiral k‐space trajectory. A series of 11 subjects were imaged using 3T MRI and combination endorectal (ER) and six‐channel phased array cardiac coils. T1W TSE and T2*W EPI sequences were analyzed quantitatively for hemorrhage contrast. Point resolved spectroscopy (PRESS MRS) was performed and data quality was analyzed.

Results:

Two types of susceptibility variation were identified: hemorrhagic and nonhemorrhagic T2*W‐positive areas. Post‐biopsy hemorrhage lesions showed on average five times greater contrast on the T2*W images than T1W TSE images. Six nonhemorrhage regions of severe susceptibility artifact were apparent on the T2*W images that were not seen on standard T1W or T2W images. All nonhemorrhagic susceptibility artifact regions demonstrated compromised spectral quality on 3D MRS.

Conclusion:

The fast T2*W EPI sequence identifies hemorrhagic and nonhemorrhagic areas of susceptibility variation that may be helpful in prostate MRI planning at 3.0T. J. Magn. Reson. Imaging 2011;33:902–907. © 2011 Wiley‐Liss, Inc.     

Post-operative lumbar spine: comparative study of TSE T2 and turbo-FLAIR sequences vs contrast-enhanced SE T1

AIM: To compare turbo T2 weighted spin echo (TSE T2) and turbo-FLAIR (fluid attenuated inversion recovery) vs gadolinium enhanced T1 weighted spin echo (SE T1) sequence in the differential diagnosis between disc herniation and post-surgical fibrosis. MATERIALS AND METHODS: Sixty-four patients who underwent surgical treatment for lumbar disc herniation with persistent or recurrent post-surgical symptoms were studied with a 0.5 Tesla MR system. The sequences used were TSE T2, turbo-FLAIR and T1 SE with and without intravenous gadolinium DTPA. The enhanced T1 SE sequence was considered the gold standard. Sensitivity and specificity were calculated. RESULTS: The sensitivity was 100% for both TSE T2 and turbo-FLAIR sequences. The specificity was 94% for TSE T2 and 92% for turbo-FLAIR. Negative predictive value was 100% for both sequences and positive predictive value 84% and 80% for TSE T2 and turbo-FLAIR, respectively. CONCLUSION: Although both sequences show high sensitivity, TSE-T2 presents greater specificity than turbo-FLAIR as compared to enhanced T1 SE. TSE T2 also offers the advantage of myelographic effect. We consider that the use of rapid sequences may avoid the need for intravenous contrast medium in most cases, reserving gadolinium DTPA only to those where all the criteria for hernia or fibrosis are not fulfilled.     

MR imaging of the liver using an ultrafast 3D multi-shot EPI sequence. Comparison with four other T1-weighted sequences.

PURPOSE: To compare a 3D echo planar imaging (EPI) sequence with four other T1-weighted sequences for imaging of the liver at 1 T. MATERIAL AND METHODS: Twenty volunteers were included in our imaging protocol. Spin-echo (SE), turbo SE (TSE), turbo field echo (TFE) in 2D and 3D acquisition mode, fast field echo (T1-FFE) and 3D EPI sequences were applied. Signal-to-noise (S/N) ratio of the liver, contrast-to-noise (C/N) ratio and relative contrast (ReCon) between the liver and the spleen, scanning time per slice and artifact levels were evaluated. RESULTS: 3D EPI provided a statistically equivalent S/N ratio of the liver with SE and T1-FFE sequences (p>0.05), while it provided a statistically higher S/ N ratio of the liver compared to TFE sequences (p<0.05). The TSE technique provided a statistically higher S/N ratio of the liver compared to 3D EPI (p<0.05). With regard to the liver-spleen C/N ratio, 3D EPI provided statistically equivalent results compared to all sequences except T1-FFE, where 3D EPI was superior. With regard to liver-spleen ReCon, 3D EPI was statistically equivalent to SE, TSE and T1-FFE, while it provided significantly higher liver-spleen ReCon than 3D TFE and significantly lower than 2D TFE. CONCLUSION: 3D EPI provided sufficient ReCon and C/N ratio and produced motion-free images in one breath-hold period. Further clinical studies are required to estimate the sensitivity, specificity and accuracy of the sequence.     

Diagnostic accuracy of staging renal cell carcinomas using multidetector-row computed tomography and magnetic resonance imaging: a prospective study with histopathologic correlation

OBJECTIVE: The aim of this prospective study is to compare the diagnostic accuracy of multidetector-row computed tomography (CT) and magnetic resonance imaging (MRI) in tumor staging of renal cell carcinomas. METHODS: In a prospective study, 82 renal cell carcinomas were assessed for tumor staging before surgery using multidetector-row CT and MRI, the results of which were then correlated to histopathologic staging. Triphasic CT (noncontrast, arterial phase, and parenchymal phase) imaging was performed using multidetector-row CT with a reconstructed slice thickness of 2 mm. In MRI, a transverse T1-weighted gradient echo sequence with and without administration of Gd-DTPA, a transverse T2-weighted respiratory-gated turbo spin echo (TSE) sequence, and a coronal T1-weighted gradient echo sequence with Gd-DTPA were used. In addition, multiphasic 3-dimensional angiography after Gd-DTPA injection and a transverse T1-weighted fat-suppression sequence were performed. RESULTS: With MRI, readers 1 and 2 correctly staged 71 and 64 tumors (overall accuracy of 0.87 and 0.78, respectively) and achieved Mantel-Haenszel chi(2) values of 66 and 63 (P < 0.0001). Computed tomography allowed correct staging of 68 and 66 tumors (readers 1 and 2, overall accuracy of 0.83 and 0.80, respectively) with Mantel-Haenszel chi(2) values of 54 and 54 for CT staging (P < 0.0001). No statistically significant difference between overall accuracy was found in the chi(2) test (P > 0.15). CONCLUSION: Magnetic resonance imaging and multidetector-row CT with its multiplanar reconstruction capabilities achieve similar accuracy in tumor staging of renal cell carcinomas.     

A comparison of pulse sequences in the detection of post-traumatic bone marrow abnormalities at low field strength MRI

Objective and patients. One hundred and forty-one patients with recent joint trauma, aged 12–71 years, were imaged on a 0.2-T dedicated MRI system and evaluated for bone bruises. The most beneficial sequences were compared. Design. The diagnosis of post-traumatic bone marrow abnormalities was established in 20 of 141 patients on the basis of decreased signal intensity on T1-weighted SE and GRE sequences and increased signal intensity on T2-weighted TSE and fat-suppressed IRGE sequences. Signal changes within the bone marrow were evaluated and statistically correlated with normal bone. Results. The highest signal alteration was found on T1-weighted SE and GRE sequences, followed by IRGE, which detected smaller differences in signal intensity. T2-weighted TSE imaging showed the least contrast. The areas with bone marrow changes were approximately equal in size on T1-weighted SE and T2-weighted TSE sequences. The same areas depicted on IRGE and GRE sequences proved to be significantly larger (P<0.01). Conclusion. Using a 0.2-T dedicated system T1-weighted SE, T1-weighted GRE and IRGE sequences were most effective in detecting conspicuous bone marrow alteration, while the T2-weighted TSE sequence was inferior. GRE and IRGE imaging showed areas about 4 times larger depicting bone marrow changes. On suspicion of bone bruise, a protocol including GRE and IRGE pulse sequences could be most beneficial.     

Asbestos-related pleural disease: value of dedicated magnetic resonance imaging techniques

OBJECTIVES: We sought to compare respiratory-gated high-spatial resolution magnetic resonance imaging (MRI) and radial MRI with ultra-short echo times with computed tomography (CT) in the diagnosis of asbestos-related pleural disease. METHODS: Twenty-one patients with confirmed long-term asbestos exposure were examined with a CT and a 1.5-T MR unit. High-resolution respiratory-gated T2w turbo-spin-echo (TSE), breath-hold T1w TSE, and contrast-enhanced fat-suppressed breath-hold T1w TSE images with an inplane resolution of less than 1 mm were acquired. To visualize pleural plaques with a short T2* time, a pulse sequence with radial k-space-sampling was used (TE = 0.5 milliseconds) before and after administration of Gd-DTPA. CT and MR images were assessed by 4 readers for the number and calcification of plaques, extension of pleural fibrosis, extrapleural fat, detection of mesothelioma and its infiltration into adjacent tissues, and detection of pleural effusion. Observer agreement was studied with the use of kappa statistics. RESULTS: The MRI protocol allowed for differentiation between normal pleura and pleura with plaques. Interobserver agreement was comparable for MRI and CT in detecting pleural plaques (median kappa = 0.72 for MRI and 0.73 for CT) and significantly higher with CT than with MRI for detection of plaque calcification (median kappa 0.86 for CT and 0.72 for MRI; P = 0.03). Median sensitivity of MRI was 88% for detection of plaque calcification compared with CT. For assessment of pleural thickening, pleural effusion, and extrapleural fat, interobserver agreement with MRI was significantly higher than with CT (median kappa 0.71 and 0.23 for pleural thickening, 0.87 and 0.62 for pleural effusion, and 0.7 and 0.56 for extrapleural fat, respectively; P < 0.05). For detection of mesothelioma, median kappa was 0.63 for MRI and 0.58 for CT. CONCLUSION: High-resolution MR sequences and radial MRI achieve a comparable interobserver agreement in detecting pleural plaques and even a higher interobserver agreement in assessing pleural thickening, pleural effusion, and extrapleural fat when compared with CT.