MR imaging of hyperacute subarachnoid and intraventricular hemorrhage at 3T: a preliminary report of gradient echo T2*-weighted sequences

We describe MR imaging findings applying gradient echo (GRE) T2*-weighted and fluid-attenuated inversion recovery (FLAIR) MR images at 3T to three patients with hyperacute subarachnoid and intraventricular hemorrhage from ruptured aneurysms. Hyperacute subarachnoid and intraventricular hemorrhages (SAH and IVH) were more clearly visualized as an area of decreased signal intensity on GRE T2*-weighted sequences than on FLAIR sequences in all three patients. These preliminary results suggest that acute SAH and IVH with GRE T2*-weighted imaging can be reliably diagnosed at 3T.     

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.     

Diffuse axonal injury associated with chronic traumatic brain injury: evidence from T2*-weighted gradient-echo imaging at 3 T

BACKGROUND AND PURPOSE: Diffuse axonal injury is frequently accompanied by tissue tear hemorrhages. We examined whether high field strength T2*-weighted gradient-echo imaging performed during the chronic stage of traumatic brain injury may have advantages in the evaluation of diffuse axonal injury as compared with T1- and T2-weighted MR imaging. METHODS: Prospective MR imaging of 66 patients (age range, 17-57 years) was performed using a 3-T system 3 to 292 months (median, 23.5 months) after traumatic brain injury. T1-, T2-, T2*-hypointense and T2-hyperintense foci of 1- to 15-mm diameter were registered in 10 brain regions by two readers separately. Foci that appeared hypointense both on the T1- and T2- and/or on the T2*-weighted images were defined as traumatic microbleeds. RESULTS: For 46 (69.7%) of the patients, T2*-weighted gradient-echo imaging revealed traumatic microbleeds. Hyperintense foci were observed on the T2-weighted images of only 15 (22.7%) patients. T2*-weighted imaging showed significantly more traumatic microbleeds (P =.000) than did T1- and T2-weighted imaging. Interobserver agreement was strong (kappa = 0.79, tau = 0.749, P =.000). For 14 (21.2%) of the patients, T2*-weighted gradient-echo imaging revealed traumatic microbleeds in the corpus callosum, whereas for only two (3%), hyperintense callosal lesions were seen on the T2-weighted images. Although a significant correlation existed between the total amount and callosal appearance of traumatic microbleeds and Glasgow Coma Scale scores (P =.000), no correlation existed with extended Glasgow Outcome Scale scores. CONCLUSION: T2*-weighted gradient-echo imaging at high field strength is a useful tool for the evaluation of diffuse axonal injury during the chronic stage of traumatic brain injury. Diffuse axonal injury-related brain lesions are mainly hemorrhagic. The relevance of diffuse axonal injury for long-term clinical outcome is uncertain.     

Importance of T2*-weighted gradient-echo MRI for diagnosis of cortical vein thrombosis

We examined six patients with isolated venous thrombosis (n = 2), or venous thrombosis combined with sinus thrombosis (n = 4) (CVT). The clinical symptoms were non-specific (acute cephalea, paresis, epileptic seizure, progressive speech disorder). All examinations were performed on a 1.5 T system (Magnetom Symphony, Siemens, Erlangen, Germany), maximum gradient field strength 30 mT/m, minimal gradient rise time 450 micros, according to the following protocol: Transverse T2-weighted turbo spin-echo (TSE), fluid attenuated inversion recovery (FLAIR), T1-weighted spin-echo (SE), before and after administration of contrast medium, T2*-weighted conventional gradient-echo (GRE), T2*-weighted spin-echo echo planar imaging (SE EPI), both without and with diffusion weighting as well as two-dimensional (2D) venous time-of-flight (TOF) MRA. The venous thromboses were best detectable in the T2*-weighted conventional GRE sequence in all patients. In two patients, the CVT was discernible only in this sequence. The sinus thrombosis was well discernible only in the T2*-weighted GRE sequence in only one case; in the remaining cases it was detectable only with difficulty. For these cases, other sequences such as SE, diffusion-weighted, or 2D-TOF-MRA sequence were superior. The T2*-weighted conventional GRE sequence was superior to the T2*-weighted SE EPI sequence in all patients. To sum up, it can be concluded, that T2*-weighted conventional GRE sequences are possibly the best method of detection of acute cortical vein thromboses. Therefore, it seems to be of benefit to integrate a T2*-weighted conventional GRE sequence into the MR-protocol for the diagnosis of isolated cortical vein thrombosis.     

Dynamic contrast-enhanced T2*-weighted MR imaging of tumefactive demyelinating lesions.

PURPOSE: Dynamic contrast-enhanced T2*-weighted MR imaging has been helpful in characterizing intracranial mass lesions by providing information on vascularity. Tumefactive demyelinating lesions (TDLs) can mimic intracranial neoplasms on conventional MR images, can be difficult to diagnose, and often result in surgical biopsy for suspected tumor. The purpose of this study was to determine whether dynamic contrast-enhanced T2*-weighted MR imaging can be used to distinguish between TDLs and intracranial neoplasms that share common features on conventional MR images. METHODS: We retrospectively reviewed the conventional and dynamic contrast-enhanced T2*-weighted MR images and medical records of 10 patients with tumefactive demyelinating disease that was diagnosed by either biopsy or strong clinical suspicion supported by laboratory evaluation that included CSF analysis and evoked potential tests. Twelve TDLs in 10 patients and 11 brain tumors that appeared similar on conventional MR images were studied. Relative cerebral blood volume (rCBV) was calculated from dynamic MR data and was expressed as a ratio to contralateral normal white matter. rCBV values from 11 patients with intracranial neoplasms with very similar conventional MR imaging features were used for comparison. RESULTS: The rCBV values of TDLs ranged from 0.22 to 1.79 (n = 12), with a mean of 0.88 +/- 0.46 (SD). The rCBV values of intracranial neoplasms ranged from 1.55 to 19.20 (n = 11), with a mean of 6.47 +/- 6.52. The difference in rCBV values between the two groups was statistically significant (P =.009). The difference in rCBV values between TDLs and primary cerebral lymphomas (n = 4) was less pronounced but was statistically significant (P =.005). CONCLUSION: Dynamic contrast-enhanced T2*-weighted MR imaging is a useful diagnostic tool in differentiating TDLs from intracranial neoplasms and may therefore obviate unnecessary surgical biopsy.     

Characterization of focal hepatic lesions with ferumoxides-enhanced MR imaging: utility of T1-weighted spoiled gradient recalled echo images using different echo times

PURPOSE: To evaluate the different signal characteristics of focal hepatic lesions on ferumoxides-enhanced MR imaging, including T1-weighted spoiled gradient recalled echo (GRE) images using different echo times (TE) and T2- and T2*-weighted images. MATERIALS AND METHODS: Ferumoxides-enhanced MR imaging was performed using a 1.5-T system in 46 patients who were referred for evaluation of known or suspected hepatic malignancies. One hundred and seven lesions (42 hepatocellular carcinomas [HCC], 40 metastases, 13 cysts, eight hemangiomas, three focal nodular hyperplasias [FNHs], and one cholangiocarcinoma) were evaluated. Postcontrast MR imaging included 1) T2-weighted FSE; 2) T2*-weighted GRE; 3) T1-weighted spoiled GRE using moderate (TE = 4.2-4.4 msec) TE; and 4) minimum (TE = 1.8-2.1 msec) TE. Signal intensities of the focal lesions were rated by two radiologists in conference as follows: hypointense, isointense or invisible, hyperintense, and markedly hyperintense. Lesion-to-liver contrast-to-noise ratio (C/N) was measured by one radiologist for a quantitative assessment. RESULTS: On ferumoxides-enhanced FSE images, 92% of cysts were "markedly hyperintense" and most of the other lesions were "hyperintense", and the mean C/N of cysts was significantly higher than that of other focal lesions. T2*-weighted GRE images showed most lesions with similar hyperintensities and the mean C/N was not significantly different between any two types of lesion. T1-weighted GRE images using moderate TE showed all FNHsand hemangiomas, 29 (69%) HCCs and eight (20%) metastases as "hyperintense". On T1-weighted GRE images using minimum TE, however, all HCCs and metastasis except one were iso- or hypointense, while all of the FNHs and hemangiomas were hyperintense. Ring enhancement was highly suggestive of malignant lesions, and was more commonly seen on the minimum TE images than on the moderate TE images. CONCLUSION: Addition of T1-weighted GRE images using minimum and moderate TE is helpful for characterizing focal lesions in ferumoxides-enhanced MR imaging.     

Diuretic-enhanced gadolinium excretory MR urography: comparison of conventional gradient-echo sequences and echo-planar imaging

The aim of this study was to investigate the utility of different gadolinium-enhanced T1-weighted gradient-echo techniques in excretory MR urography. In 74 urologic patients, excretory MR urography was performed using various T1-weighted gradient-echo (GRE) sequences after injection of gadolinium-DTPA and low-dose furosemide. The examinations included conventional GRE sequences and echo-planar imaging (GRE EPI), both obtained with 3D data sets and 2D projection images. Breath-hold acquisition was used primarily. In 20 of 74 examinations, we compared breath-hold imaging with respiratory gating. Breath-hold imaging was significantly superior to respiratory gating for the visualization of pelvicaliceal systems, but not for the ureters. Complete MR urograms were obtained within 14–20 s using 3D GRE EPI sequences and in 20–30 s with conventional 3D GRE sequences. Ghost artefacts caused by ureteral peristalsis often occurred with conventional 3D GRE imaging and were almost completely suppressed in EPI sequences (p < 0.0001). Susceptibility effects were more pronounced on GRE EPI MR urograms and calculi measured 0.8–21.7 % greater in diameter compared with conventional GRE sequences. Increased spatial resolution degraded the image quality only in GRE-EPI urograms. In projection MR urography, the entire pelvicaliceal system was imaged by acquisition of a fast single-slice sequence and the conventional 2D GRE technique provided superior morphological accuracy than 2D GRE EPI projection images (p < 0.0003). Fast 3D GRE EPI sequences improve the clinical practicability of excretory MR urography especially in old or critically ill patients unable to suspend breathing for more than 20 s. Conventional GRE sequences are superior to EPI in high-resolution detail MR urograms and in projection imaging. Received: 12 May 2000 Revised: 14 July 2000 Accepted: 17 July 2000     

Intratumoral microhemorrhages on T2*-weighted gradient-echo imaging helps differentiate vestibular schwannoma from meningioma

BACKGROUND AND PURPOSE: Vestibular schwannomas (VS) may be difficult to differentiate from cerebellopontine angle (CPA) meningiomas. Demonstration of microhemorrhages in VS on T2*-weighted gradient-echo (GRE) sequences may have potential value to differentiate VS from CPA meningiomas.Materials and METHODS: In this prospective study of 20 patients, MR imaging was performed with T2*-weighted GRE in addition to all basic sequences. Histopathologic examination was performed after surgery. Intratumoral hemosiderin was confirmed by pigment staining.RESULTS: There were 15 patients in the VS group with 16 VS and 5 in the meningioma group with 5 posterior fossa meningiomas. Fourteen of the 16 VS and all 5 meningiomas were treated surgically and were confirmed on histopathologic examination. T2*-weighted GRE identified microhemorrhages on T2*-weighted sequence in 15 (93.75%) of the 16 VS. CT excluded calcification in all VS. T2-weighted turbo spin-echo (TSE) and fluid-attenuated inversion recovery (FLAIR) images recognized microhemorrhages in 2 cases. Pigment staining confirmed hemosiderin in all 14 surgically treated VS, and none of the meningiomas showed microhemorrhages on MR imaging. For the detection of microhemorrhages, T2*-weighted GRE showed a sensitivity of 93.8%, specificity of 100%, positive predictive value of 100%, and negative predictive value of 83.3%. The sensitivity of T2 TSE and FLAIR for microhemorrhage was 12.5%. The Fisher exact test showed a statistically significant difference in the differentiation of VS from meningioma on the basis of detection of microhemorrhages (P < .01).CONCLUSION: Most VS demonstrate microhemorrhages on T2*-weighted GRE. This finding is useful to differentiate VS from CPA meningiomas. T2*-weighted GRE should be used as a basic sequence to evaluate CPA tumors. Identification of microhemorrhages may have the potential to assess the aggressive biologic behavior of VS.

Vestibular schwannomas (VS) and meningiomas comprise most cerebellopontine angle (CPA) tumors. VS constitute 80% to 90% and meningiomas 10% to 15% of CPA tumors.¹ It is essential to distinguish these 2 lesions accurately before surgery because the outcome with preservation of hearing is better with meningiomas.¹ MR imaging is considered the imaging method of choice to assess CPA tumors and to distinguish VS from meningiomas. A tumor in the internal auditory canal (IAC) with dilation of the canal is highly suggestive of VS. Signs such as the presence of hyperostosis, calcification, broad base of the tumor against the tentorium, and a dural tail may favor the diagnosis of a meningioma.² However, both VS and meningioma may show similar imaging features, and hence it is not surprising that approximately 25% of CPA meningiomas are mistaken for VS.³ Identification of microhemorrhages may be of interest to assess its relationship to the development of cystic changes in VS and to identify cases at risk of developing clinically significant intratumoral bleed. To our knowledge, no previous study has been done with T2*-weighted gradient-echo (GRE) sequence to assess the presence of intratumoral microhemorrhages and its diagnostic potential in identifying VS.     

Dynamic contrast-enhanced T2*-weighted MR imaging of gliomatosis cerebri

BACKGROUND AND PURPOSE: MR imaging characteristics of gliomatosis cerebri reiterate the diffuse nature of this tumor but are nonspecific and thus may pose a diagnostic challenge. Because perfusion MR imaging can provide a physiologic map of the microcirculation, we compared the measured relative cerebral blood volume (rCBV) at perfusion imaging with histopathologic findings in gliomatosis cerebri. MR spectroscopic findings were also reviewed. METHODS: Retrospective analysis was performed of conventional and perfusion MR images from seven patients with proved gliomatosis cerebri. The conventional MR images were evaluated for the presence or absence of contrast enhancement, necrosis, and extent of T2-weighted signal intensity abnormality. Dynamic contrast-enhanced T2*-weighted gradient-echo echo-planar images were acquired during the first pass of a bolus injection of gadopentetate dimeglumine. The rCBV was calculated by using nondiffusible tracer kinetics and expressed relative to normal-appearing white matter. Pathologic findings were reviewed in all patients and compared with the MR perfusion data. Multivoxel 2D chemical shift imaging proton MR spectroscopic data were available for three patients and single-voxel data for one patient. RESULTS: Conventional MR images showed diffuse abnormality in all cases and absence of contrast enhancement in all but one case. Average rCBV range was 0.75-1.26 (mean, 1.02 +/- 0.42 [SD]). MR spectroscopic data revealed spectra consistent with presence of tumoral disease. Histopathologic review showed absence of vascular hyperplasia in all specimens. CONCLUSION: The low MR rCBV measurements of gliomatosis cerebri are in concordance with the lack of vascular hyperplasia found at histopathologic examination; thus, perfusion MR imaging provides useful adjunctive information that is not available from conventional MR imaging techniques.     

Assessment of hemorrhage in pituitary macroadenoma by T2*-weighted gradient-echo MR imaging

BACKGROUND AND PURPOSE: Intratumoral hemorrhage occurs frequently in pituitary macroadenoma and manifests as pituitary apoplexy and recent or old silent hemorrhage. T2*-weighted gradient-echo (GE) MR imaging is the most sensitive sequence for the detection of acute and old intracranial hemorrhage. T2*-weighted GE MR imaging was used to investigate intratumoral hemorrhage in pituitary macroadenomas. MATERIALS AND METHODS: Twenty-five consecutive patients who underwent total or subtotal resection of pituitary macroadenoma with heights from 17 to 53 mm, including 1 patient with classic pituitary apoplexy, underwent MR imaging before surgery, including T2*-weighted GE MR imaging. For histologic assessment of the hemorrhage in whole surgical specimens, we used hematoxylin-eosin staining. RESULTS: T2*-weighted GE MR imaging detected various types of dark lesions, such as "rim," "mass," "spot," and "diffuse" and combinations, indicating clinical and subclinical intratumoral hemorrhage in 12 of the 25 patients. The presence of intratumoral dark lesions on T2*-weighted GE MR imaging correlated significantly with the hemorrhagic findings on T1- and T2-weighted MR imaging (P < .02 and <.01, respectively), and the surgical and histologic hemorrhagic findings (P < .001 and <.001, respectively). CONCLUSION: T2*-weighted GE MR imaging could detect intratumoral hemorrhage in pituitary adenomas as various dark appearances. Therefore, this technique might be useful for the assessment of recent and old intratumoral hemorrhagic events in patients with pituitary macroadenomas.     

Adrenal tissue characterization with 0.5-T MR imaging: Value of T2*-weighted images

The authors investigated the value of magnetic resonance (MR) imaging at 0.5 T for distinguishing adrenal adenomas from adrenal metastases. The series included 23 adrenal adenomas (18 nonhyperfunctioning, five hyperfunctioning) and 23 adrenal metastases from various organs. Adrenal tumor–liver signal intensity ratios on T1-, T2-, and T2*-weighted images were calculated for adrenal tissue characterization. Adrenal adenomas were more precisely distinguished from adrenal metastases on T2*-weighted images (21 of 23, 91%) than on T2-weighted images (15 of 23, 65%). T1-weighted images were not useful for this distinction. In conclusion, T2*-weighted images were better than routine T2-weighted images for distinguishing adrenal adenomas from adrenal metastases. It can be postulated that the total signal intensity of adrenal adenomas, which contain some fat components, decreased on T2*-weighted images because of an out-of-phase effect.     

Fast MR imaging of liver metastasis using FLASH and FISP--optimal sequences for T1- and T2*-weighted images

This paper deals with a study to obtain the optimal sequence of gradient echo (GE) for T1- and T2*-weighted images similar to T1- and T2-weighted images of spin echo (SE). Two GE sequences, fast low angle shot (FLASH) and fast imaging with steady-state precession (FISP), were performed in 15 cases of liver metastasis in various combination of flip angle (FA), repetition time (TR), and echo time (TE). The optimal combinations were summarized as follows: 1) T1-weighted FLASH image with FA of 40 degrees, TR of 22 msec and TE of 10 msec, 2) T1-weighted FISP image with FA of 70 degrees, TR of 100 msec, TE of 10 msec, 3) both T2*-weighted FLASH and FISP images with FA of 10 degrees, TR of 100 msec and TE of 30 msec. Not only to provide the adequate T1- and T2*-weighted images but also to enable breath-holding MR imaging, GE sequences can optionally take place SE in cases of deteriorated images caused by moving artifacts. Other applications support the re-examination and further detailing when required, conveniently rather in short time.     

MR imaging of liver metastases at 1.5 T: similar contrast discrimination with T1- and T2-weighted pulse sequences

The authors evaluated soft-tissue contrast on spin-echo (SE) proton density-weighted, SE T2-weighted, SE short-echo-time (TE) T1-weighted, and gradient-echo (GRE) images of 34 patients with known hepatic tumors who underwent high-field-strength (1.5-T) magnetic resonance imaging. For solid liver tumors, the difference in the mean lesion-liver contrast-to-noise ratios (C/Ns) with T1- (GRE and SE) and T2-weighted pulse sequences was not statistically significant (P greater than .05). For nonsolid liver tumors, the T2-weighted images provided significantly greater (P less than .05) mean lesion-liver C/N than T1-weighted GRE images. Mean liver signal-to-noise ratio was significantly greater on T1-weighted GRE (P less than .0001) and T1-weighted SE (P less than .05) images than on T2- and proton density-weighted images. Qualitative analysis of T1-weighted (SE and GRE) images and proton density- plus T2-weighted images showed that lesion conspicuity was similar in 25 of 32 patients (78%). The results suggest that liver tumor imaging at high field strength can be performed with short-TE T1-weighted (SE or GRE) or conventional T2-weighted pulse sequences.     

Improved detection of metastatic melanoma by T2*-weighted imaging

BACKGROUND AND PURPOSE: The imaging features of metastatic melanomas are distinctive due to the presence of melanin and the propensity for hemorrhage. Both hemorrhage and melanin can produce T1-weighted hyperintensity and T2*-weighted signal intensity loss. We hypothesized that T2*-weighted images would improve detection of metastatic melanoma. METHODS: The T2* and T1 characteristics of 120 newly detected metastatic brain lesions from 31 patients with malignant melanoma were compared with those of 120 brain metastases from 23 patients with lung cancer. RESULTS: Melanoma metastases were 5 times more likely to demonstrate prominent T2*-related signal intensity loss (susceptibility effect) than were lung metastases (42% vs 8%; P < .01), and 4.5 times more likely to demonstrate T1 hyperintensity (55% vs 12%; P < .01). Patients with melanoma had lesions that were either hypointense on T2*-weighted images, hyperintense on T1 images, or both, in 71% (85/120), compared with 19% (23/120) of lung carcinoma metastases (P < .01). Melanoma lesions were 16 times more likely than lung cancer lesions to show combined T2* related signal intensity loss and T1 hyperintensity (P < .01). Remarkably, 8 melanoma lesions (7%) in 3 patients were detectable principally on the T2*-weighted sequences, whereas no lung cancer lesion was detected solely on susceptibility images. We found a direct correlation between melanin content and T1 hyperintensity but no correlation between T2* intensity and melanin. CONCLUSION: T2*-weighted images improve lesion detection in patients with melanoma metastases, and in conjunction with T1-weighted sequences, can suggest melanoma as the etiology of an intracranial mass. This sequence should be employed for evaluation of possible brain metastasis in patients without a known primary malignancy and in studies for melanoma staging.     

MRI of acute post-ischemic cerebral hemorrhage in stroke patients: diagnosis with T2*-weighted gradient-echo sequences

The use of T2^*-weighted sequences has been advocated for early differentiation between hematoma and ischemia in patients with acute stroke. Early hemorrhagic transformation of ischemic stroke is an adverse event which may occur under treatment and may impair the prognosis: our aim is to evaluate the ability of T2*-weighted gradient-echo sequence (T2^* GRE) to detect post-ischemic cerebral hemorrhage. The imaging procedure included: (1) baseline CT scan at admission. (2) MRI performed within 24 h of therapy onset including: (a) dual fast spin echo T2 sequence, (b) axial isotropic echoplanar diffusion-weighted imaging sequence, (c) conventional T2* GRE, and (d) 3D TOF turbo MRA. Post-ischemic cerebral hemorrhage was diagnosed if T2^* GRE detected a focal intraparenchymal area of signal loss. The diameter of this lesion had to be more than 5 mm in order to eliminate past microbleeds. (3) Patients who showed an early suspicion of bleeding on MRI promptly had a second CT scan, and, if this one was negative for bleeding, another CT scan was performed 1 day later. All the other patients had a control CT scan during the first week. Forty-five consecutive patients have been included. T2* GRE showed intracranial bleeding in seven. The diagnosis of post-ischemic cerebral bleeding was confirmed by CT in all patients. Control CT scans did not reveal any post-ischemic cerebral hemorrhage in patients with negative MRI. In one case, hemorrhage was seen earlier on MRI than on CT scan. In conclusion, T2^* GRE appeared to be at least as efficient as CT scan in the detection of early post-ischemic cerebral hemorrhage. Received: 30 October 2000/Accepted: 23 March 2001     

Histopathologic analysis of foci of signal loss on gradient-echo T2*-weighted MR images in patients with spontaneous intracerebral hemorrhage: evidence of microangiopathy-related microbleeds.

BACKGROUND AND PURPOSE: Patients with spontaneous intracerebral hemorrhage (ICH) frequently have small areas of signal loss on gradient-echo T2*-weighted MR images, which have been suggested to represent remnants of previous microbleeds. Our aim was to provide histopathologic support for this assumption and to clarify whether the presence and location of microbleeds were associated with microangiopathy. METHODS: We performed MR imaging and correlative histopathologic examination in 11 formalin-fixed brains of patients who had died of an ICH (age range, 45-90 years). RESULTS: Focal areas of signal loss on MR images were noted in seven brains. They were seen in a corticosubcortical location in six brains, in the basal ganglia/thalami in five, and infratentorially in three specimens. Histopathologic examination showed focal hemosiderin deposition in 21 of 34 areas of MR signal loss. No other corresponding abnormalities were found; however, hemosiderin deposits were noted without MR signal changes in two brains. All specimens with MR foci of signal loss showed moderate to severe fibrohyalinosis, and there was additional evidence of amyloid angiopathy in two of those brains. CONCLUSION: Small areas of signal loss on gradient echo T2*-weighted images indicate previous extravasation of blood and are related to bleeding-prone microangiopathy of different origins.     

Magnetic resonance imaging of the cervical spine: comparison of 2D T2-weighted turbo spin echo, 2D T2*weighted gradient-recalled echo and 3D T2-weighted variable flip-angle turbo spin echo sequences

To compare an isotropic three-dimensional (3D) high-resolution T2-weighted (w) MR sequence and its reformations with conventional sequences for imaging of the cervical spine. Fifteen volunteers were examined at 1.5 T using sagittal and axial 3D T2-w, sagittal and axial 2D T2w, and axial 2D T2*w MR sequences. Axial reformations of the sagittal 3D dataset were generated (3D MPR T2w). Signal-to-noise and image homogeneity were evaluated in a phantom and in vivo. Visibility of ten anatomical structures of the cervical spine was evaluated. Artifacts were assessed. For statistical analysis, Cohen’s kappa, Wilcoxon matched pairs, and t-testing were utilized. There were no significant differences in homogeneity between the sequences. Sagittal 3D T2w enabled better delineation of nerve roots, neural foramina, and intraforaminal structures compared to sagittal 2D T2w. Axial 3D T2w and axial 3D MPR T2w resulted in superior visibility of most anatomical structures compared to axial 2D T2w and comparable results to 2D T2*w concerning the spinal cord, nerve roots, intraforaminal structures, and fat. Artifacts were most pronounced in axial 2D T2w and axial 3D T2w. Acquisition of a 3D T2w data set is feasible in the cervical spine with superior delineation of anatomical structures compared to 2D sequences.     

MR梯度回波T2^＊WI检出脑微出血

目的：MR梯度回波T2^＊WI可检出无症状性脑微出血,本研究旨在探讨脑微出血的发生率、部位以及与高血压、脑卒中、脑室周围白质高信号的相关性。方法：在1年时间内共有375例患者在常规MRI／序列的基础上加扫T2^＊加权序列,排除了存在脑血管畸形出血、颅内占位、外伤、手术史等病例,共有324例进行分析处理。结果：脑微出血37例,总的发生率为11．4％,尤其位于基底节／放射冠（n=22）、丘脑（n=15）、小脑（n=14）和脑叶区域（n=15）,脑微出血主要见于存在脑中风史病例,与年龄、高血压、脑白质疏松症（脑室周围白质高信号）存在相关性（P〈0．001）。在2年多的影像学随访过程中,共发现2例（5．4％）出现新鲜脑出血。结论：MR T2^＊加权像可用于检出脑微出血,其发生提示存在脑微小血管病变,存在继发出血的可能性,建议对于60岁以上的老年人尤其是存在脑中风的病例,MR T2^＊加权应作为常规扫描序列。     

Anteroinferior tears of the glenoid labrum: fat-suppressed fast spin-echo T2 versus gradient-recalled echo MR images

 Objective. To compare fat-suppressed fast spin-echo (FSE) T2-weighted images with gradient-recalled echo (GRE) T2*-weighted images in the evaluation of anteroinferior labral tears. Design. MR images were retrospectively reviewed by two radiologists masked to the history and arthroscopic findings. They separately interpreted the anteroinferior labrum as torn or intact, first on one pulse sequence and then, 4 weeks later, on the other sequence. The MR interpretations were correlated with the arthroscopic findings. Patients. Nine patients with anteroinferior labral tears, and nine similarly-aged patients with normal, labra were studied. Results and conclusions. Observer 1 had a sensitivity of 0.56 on the GRE images and 0.67 on the FSE images (P>0.5), with a specificity of 1.0 for both sequences. Observer 2 had a sensitivity of 0.78 and a specificity of 0.89 for both sequences. In this small study there is no significant difference between GRE and fat-suppressed FSE images in their ability to diagnose anteroinferior labral tears. When evaluating the labrum with conventional MRI, axial fat-suppressed FSE T2-weighted images can be used in place of GRE images without a loss of accuracy.     

Breast lesions: evaluation with dynamic contrast-enhanced T1-weighted MR imaging and with T2*-weighted first-pass perfusion MR imaging

PURPOSE: To evaluate the diagnostic value of an imaging protocol that combines dynamic contrast-enhanced T1-weighted magnetic resonance (MR) imaging and T2*-weighted first-pass perfusion imaging in patients with breast tumors and to determine if T2*-weighted imaging can provide additional diagnostic information to that obtained with T1-weighted imaging. MATERIALS AND METHODS: One hundred thirty patients with breast tumors underwent MR imaging with dynamic contrast-enhanced T1-weighted imaging of the entire breast, which was followed immediately with single-section, T2*-weighted imaging of the tumor. RESULTS: With T2*-weighted perfusion imaging, 57 of 72 carcinomas but only four of 58 benign lesions had a signal intensity loss of 20% or more during the first pass, for a sensitivity of 79% and a specificity of 93%. With dynamic contrast-enhanced T1-weighted imaging, 64 carcinomas and 19 benign lesions showed a signal intensity increase of 90% or more in the first image obtained after the administration of contrast material, for a sensitivity of 89% and a specificity of 67%. CONCLUSION: T2*-weighted first-pass perfusion imaging can help differentiate between benign and malignant breast lesions with a high level of specificity. The combination of T1-weighted and T2*-weighted imaging is feasible in a single patient examination and may improve breast MR imaging.