MR-angiogram-added surface anatomy scanning of superficial cerebral arteriovenous malformations

Our purpose was to evaluate the utility of surface anatomy scanning (SAS) of the brain with superimposition of MR angiograms in the diagnosis and presurgical planning of superficial cerebral arteriovenous malformations (AVMs). We performed SAS in 15 patients with superficial cerebral AVMs. Two-dimensional phase-contrast MR angiograms were then obtained in the same section and superimposed on the SAS images. The images were assessed regarding the visualization of each AVM component using a four-point grading scale (3=excellent to 0=poor). In 13 of the patients, the assessment was made comparing with conventional angiograms. The images were also compared with the surgical findings in 5 patients. The added images agreed well with the angiographic findings and demonstrated the relationships between the AVM components and the adjacent brain surface. The average scores of the feeder(s), nidus, and drainer(s) were 2.27, 2.33, and 2.67, respectively. The surgical findings also correlated well with the added images. Our technique can noninvasively demonstrate superficial AVMs along with the brain surface and provide information useful for planning surgery.     

A new MRI technique for demonstrating the surface of the brain together with the cortical veins

We assessed combining of surface-anatomy scanning (SAS) MRI and MR venography (MRV). We obtained SAS images with a half-Fourier single-shot fast spin-echo sequence, then MRV of the identical section with a two-dimensional phase-contrast technique. We then added the two sets of images. The combined images, which were obtained within 10 min, provided information about the surface anatomy and cortical veins. This simple technique is useful for demonstrating brain surface structures, especially in patients from whom one plans to excise a lesion. Received: 3 August 1998 Accepted: 2 November 1998     

EEG scalp electrode projection onto three-dimensional surface rendered images of the brain

A technique is described for generating magnetic resonance-based, surface rendered images of the brain with electroencephalographic (EEG) scalp electrode positions projected onto the cortical surface. This technique (EEG electrode projection) was used in 10 patients who subsequently underwent surgery for medically intractable frontal lobe epilepsy. In most cases of intractable epilepsy, successful surgery entails the resection of electrophysiologically abnormal cortical tissue rather than an identifiable mass lesion. EEG electrode projection is a unique and useful surgical tool because it provides images that spatially correlate the surface anatomy of the brain and the electrophysiologic abnormality recorded at the scalp. Excellent correlation was found between cortical topography delineated by the surface rendered images and cortical anatomy at surgery. Agreement between EEG electrode projection and electrocorticography as to the location of the electrophysiologic abnormality increases confidence that appropriate cortical areas have been identified for resection. The technique provides new and unique insight into important anatomic-electrophysiologic relationships and aids in formulation of surgical strategy.     

Magnetic resonance imaging findings of angiosarcoma of the scalp

OBJECTIVE: The purpose of this study was to investigate the magnetic resonance (MR) imaging findings of angiosarcoma of the scalp retrospectively. METHODS: Eight patients with angiosarcoma of the scalp were included in this study. All patients were examined with 1.5-T MR imaging units and commercially available head coils. RESULTS: In all 8 patients, MR images revealed thickened scalp or tumors with prolonged T1 and T2 relaxation times. They were well enhanced. T2-weighted MR imaging with fat saturation and contrast-enhanced T1-weighted MR imaging with fat saturation clearly showed tumors invading the subcutaneous fat tissue and muscles. In 4 patients, the tumors were larger on MR images than on inspection. CONCLUSIONS: Magnetic resonance imaging was useful in determining the extent of angiosarcoma of the scalp because it visualized the tumor invasion into surrounding structures that could not be seen on physical inspection.     

Use of MR angiography for stereotactic planning.

With the introduction of MR angiography (MRA) into clinical routine MR protocols, it has become possible now to image flowing as well as stationary tissue with excellent contrast using a single modality. This has opened up new perspectives for planning stereotactic approaches, which are characterized by high risks for damaging intracerebral vessels or vital brain structures. In this article we present an MRA based planning method for the treatment of arteriovenous malformations by stereotactic radiosurgery. It includes flow compensated gradient echo pulse sequences for the acquisition of angiographic MR datasets, a stereotactic MR marker system, an algorithm for the correction of geometric distortion of MR image data, and a three-dimensional workstation system for the creation and evaluation of treatment plans. The latter is based on the concept of simultaneously displaying both MR slice and angiographic projection images. This allows the evaluation of intracerebral vasculature together with brain anatomy. The MRA guided planning approach was tested and compared to a conventional X-ray angiographic technique in a clinical study. Our satisfactory results suggest that MRA is a technique that can be used advantageously for stereotactic planning.     

眼眶病变的SPIR磁共振成像

目的：评价SPIR（用于化学位移脂肪抑制的频谱预饱和反转复位技术)与造影增强联合应用在眼眶病变判断中的作用。材料和方法：20例眼眶病变患者在Gd—DTPA增强前后，分别采用T1加权SPIR技术(飞利浦ACS Gyroscan)．以四级评分系统与常规T1加权和T2加权图像作比较．5例无眼眶病变者用来研究正常眼眶解剖。结果：由于高信号脂肪和正常结构的平均容积加上化学性位移伪影在常规MRI图像上难以清楚地勾画出眼眶解剖结构．SPIR图像能清晰显示不能增强的视神经和能显著强化的眼直肌群和泪腺。SPIR技术在眼眶病变的判断中较常规MRI图像为优。结论：SPIR技术与Gd-DTPA注射联合应用．在显示眼眶解剖上要优于常规MRI．它增强了强化病变的显著性，应常规应用于眼眶病变检查。因此，增强后的SPIR能替代增强后的T1加权图像，SPIR的不利是由于气-骨界面信号衰减伪影的出现。     

Perianal complications of Crohn disease: MR imaging findings

The aim of this study was to revisit anal anatomy, to explain surgical terminology in perianal complications of Crohn disease, and to show the MR imaging findings of perianal fistulas and abscesses. To this end more than 200 patients were studied using surface coils (Helmholtz; phased array) at 1.0 and 1.5 T. Transverse and coronal T1- and T2-weighted images were obtained. Parks' classification was used to describe perianal abscesses and fistulas. This pictorial essay shows the normal anal anatomy and pathologic findings such as subcutaneous, para-anal, ischiorectal, intersphincteric, and supralevatoric abscesses and fistulas. MR imaging with surface coils is well suited to showing the anal anatomy and to reliably describing perianal abscesses and fistulas according to surgical terminology. Received: 7 October 1996; Revision received 4 December 1996; Accepted 10 December 1996     

Comprehensive MR imaging in the preoperative evaluation of living donor candidates for laparoscopic nephrectomy: initial experience

PURPOSE: To evaluate the accuracy of magnetic resonance (MR) imaging in the preoperative evaluation of potential living renal donors who are candidates for laparoscopic nephrectomy. MATERIALS AND METHODS: Twenty-eight donor candidates who underwent subsequent laparoscopic nephrectomy were examined by using a torso phased-array coil at 1.5 T. Gadolinium-enhanced MR angiograms, MR venograms, and MR urograms were obtained in all patients by using an interpolated three-dimensional T1-weighted spoiled gradient-echo sequence (3.4-6.8/1.2-2.3 [repetition time msec/echo time msec], 25 degrees -40 degrees flip angle). Interpretation of the MR images was used to assess the arterial, venous, and ureteral anatomy, as well as parenchymal masses and scarring, and findings were compared with the surgical findings in all patients. Statistical evaluation was performed, with the surgical findings as the reference standard. RESULTS: At MR imaging, 31 of 32 renal arteries and one of three early-branching arteries were identified correctly. The correct venous anatomy was identified in 23 of 28 patients, including a single left renal vein anterior to the aorta (n = 16), retroaortic left renal vein (n = 2), circumaortic left renal vein (n = 2), and single right renal vein (n = 3). A single collecting system in all harvested kidneys was identified correctly with MR urography. Overall, MR imaging correctly depicted vascular, ureteral, and parenchymal anatomy in 21 of 28 patients. Twenty-seven of 28 patients underwent successful laparoscopic donor nephrectomy on the basis of the MR findings. One procedure was converted to open nephrectomy on the basis of complex venous anatomy not prospectively identified on the MR images. The sensitivity and positive predictive value of MR imaging in correctly determining the combined vascular, ureteral, and parenchymal anatomy in the harvested kidney were 75% (21 of 28) and 95% (21 of 22), respectively. CONCLUSION: Comprehensive gadolinium-enhanced MR imaging can depict the vascular anatomy, collecting system, and renal parenchyma preoperatively in patients who are candidates for laparoscopic living-donor nephrectomy.     

MR Imaging of Hair and Scalp for the Evaluation of Androgenetic Alopecia

Purpose:Although androgenetic alopecia (AGA) is a common cause of hair loss, little is known regarding the magnetic resonance imaging (MRI) of the AGA or scalp. This study aimed to analyze whether MRI for hair and scalp (MRH) can evaluate anatomical changes in the scalp caused by AGA.Methods:Twenty-seven volunteers were graded for the severity of AGA using the Hamilton–Norwood Scale (HNS), commonly used classification system. All subjects underwent MRH; two radiologists independently analyzed the images. As a quantitative measurement, the number of hair follicles was analyzed and compared with the HNS. As a qualitative analysis, each MRH scan was visually graded in terms of the severity of alopecia, using a 4-point MR severity score. The scores were compared with the HNS.Results:The volunteers were divided into two groups of 12 and 15 males without and with AGA at their vertex, respectively. Inter-observer agreements for the hair count and the MR severity score were excellent. The mean hair count on MRI in the normal group was significantly higher than that in the AGA group (P < 10⁻⁴). The MR severity score in the AGA group was significantly more severe than that in the control group (P < 10⁻⁴). In terms of the presence or absence of thinning hair, the MR severity score was consistent with the HNS determined by a plastic surgeon in 96% of cases. MR severity scores of clinically moderate AGA cases were significantly lower than those of severe cases (P = 0.022).Conclusion:MRH could depict scalp anatomy showing a clear difference between AGA and normal scalps, in both hair count and subjective visual assessment. The MR severity score was in good agreement with the clinical stages by HNS. The results support the potential of MRH as a promising imaging technique for analyzing healthy and pathological scalps.     

Application of surface coils to MR anatomy of the larynx

The magnetic resonance (MR) scans of 10 patients with normal larynges were compared with cryomicrosections of two injected cadaver specimens. The MR images were obtained with a solenoid surface coil and high-resolution technique that provided images 4 mm thick displayed on a 256 X 256 matrix. The improved signal-to-noise ratio of the surface coil allowed a detailed study of normal anatomy in the axial, coronal, and sagittal planes.     

Magnetic resonance imaging of the heart: a review of the experience in 172 subjects

Gated magnetic resonance (MR) imaging was used to evaluate central cardiovascular anatomy in 172 subjects, 31 of whom were healthy volunteers. Using the spin-echo technique, images of diagnostic quality were obtained in 93% of cases with TE = 28 msec and in 65% of cases with TE = 56 msec. Transverse multisection sequences encompassing most of the left ventricle required approximately 6-8 minutes. Corroborative studies were available in 134 of 141 patients who had cardiovascular disease; two dimensional echocardiograms and angiography in 133 and 100 patients, respectively. Gated MR demonstrated the wall thinning and complications caused by prior myocardial infarctions and high signal intensity of the myocardium at the site of acute myocardial infarctions. MR accurately demonstrated anatomic abnormalities owing to hypertrophic and congestive cardiomyopathies, congenital abnormalities of the heart and great vessels, rheumatic heart disease, pulmonary hypertension, and cardiac and paracardiac masses. Depiction of cardiovascular anatomy and pathoanatomy was attained without the use of any contrast media. Consequently, gated MR is an effective technique for cardiac diagnosis. The short time required for tomographic examination of the entire heart using the multisection technique renders this a practical cardiac imaging modality.     

MR imaging of brain surface structures: surface anatomy scanning (SAS)

Summary MR imaging technique that permits direct and non-invasive visualization of brain surface structures (Surface Anatomy Scanning, SAS) was developed using the combination of long TE, long TR spin echo sequence and thick slice. Clinical trials in 67 patients with SAS showed excellent visualization of the sulci and the gyri on the lateral, occipital, frontal and parietal surfaces of the brain together with cortical and subcortical lesions. The results indicate that the SAS is useful for the localization of cortical and subcortical pathology, for the diagnosis of anomalous gyral patterns, and for surgical planning.     

Peyronie's disease: MR findings in 28 patients.

Induratio penis plastica (Peyronie's disease) is a chronic fibrotic process involving the penis. Proper treatment of the disease requires assessment of the degree of inflammation preceding or accompanying the fibrous Peyronie's plaques. Owing to its high tissue contrast and its multiplanar capability, MR imaging offers excellent visualization of penile anatomy. To determine the usefulness of MR imaging in the diagnosis and staging of Peyronie's disease, we used MR imaging with a surface coil to examine 28 consecutive patients with clinical evidence of the disease. Eighteen patients had contrast-enhanced MR imaging with gadopentetate dimeglumine. In seven patients who subsequently had surgery or biopsy, MR findings were correlated with histopathologic findings. On unenhanced images, fibrous plaques were shown in 20 patients. Enhanced MR images showed focal contrast enhancement around or within the plaques in seven patients. Images in three patients with plaques showed no enhancement. Images in five patients showed focal areas of contrast enhancement without evidence of plaques. Histologic studies demonstrated that the degree of contrast enhancement correlated with the extent of inflammatory cell infiltration. In two patients with unenhancing plaques on MR, histology confirmed the absence of inflammation. Our results suggest that MR imaging not only depicts the localization and extent of fibrous plaques in patients with Peyronie's disease but also reveals the presence of inflammation. This makes MR imaging the technique of choice for planning therapy and for evaluating the response to conservative treatment.     

High-resolution 3DFT MR imaging of the endolymphatic duct and soft tissues of the otic capsule

This study compares the visualization of otic capsule anatomy by thin-section three-dimensional Fourier transformation (3DFT) MR imaging with that by high-resolution CT. The osseous margins of the otic capsule are delineated by high-resolution CT, while MR displays the soft-tissue structures. Routine two-dimensional Fourier transformation (2DFT) spin-echo MR techniques have been limited by slice thickness and signal to noise. Previous longer TE 3DFT gradient-echo MR images of the otic structures have been degraded by magnetic susceptibility effects, which limit spatial resolution and decrease signal to noise. These effects are especially prevalent in the otic capsule, where small soft-tissue structures interface with surrounding air and bone. We developed a high-resolution 3DFT MR technique to image five normal subjects. MR images were compared with high-resolution CT images of the same subjects. Axial, sagittal, and coronal 3DFT gradient-echo MR images with a short TR/TE and 15 degrees flip angle were acquired on a General Electric 1.5-T Signa unit using a 3-in. circular, receive-only surface coil. Axial, sagittal, and coronal 1.5-mm-thick contiguous high-resolution CT bone-algorithm images were obtained also. There was a high correlation between the MR and CT findings. The 3DFT MR images demonstrated significantly higher spatial resolution and soft-tissue detail than the high-resolution CT images did. For example, the endolymphatic duct was seen on twice the number of consecutive sagittal and axial MR slices. Other soft-tissue otic capsule structures routinely seen on the 3DFT MR images included the entire facial nerve, membranous labyrinth including cochlea, and tensor tympani muscle. This study demonstrates a new high-resolution 3DFT MR technique for visualizing the soft-tissue microstructures of the otic capsule and achieves a level of spatial resolution beyond that possible with high-resolution CT.     

Dynamic contrast-enhanced three-dimensional MR imaging of liver parenchyma: source images and angiographic reconstructions to define hepatic arterial anatomy

PURPOSE: To assess the accuracy of an interpolated breath-hold T1-weighted three-dimensional (3D) gradient-echo (GRE) magnetic resonance (MR) imaging sequence with near-isotropic pixel size (相似文献   

Integrated 3D display of brain anatomy and intracranial vasculature in MR imaging

In many clinical situations neuroradiologists and neurosurgeons are keenly interested in images displaying both brain structures and intracranial vessels in an integrative manner. In this paper an approach to three-dimensional visualization of brain and vascular structures from magnetic resonance (MR) volume data is reported. It has been designed with the aim of providing a robust and reliable image processing tool for routine clinical applications. The method has been made possible by recent developments in MR image acquisition, especially MR angiography and rapid gradient-echo sequences (Turbo-fast low angle shot). On the basis of the ray-tracing principle, integration of brain and vessel anatomy into a single 3D image is achieved. Image data are acquired with flow-compensated gradient-echo pulse sequences. Even slow flow in venous structures may be demonstrated using a two-dimensional sequential-slice scanning method. Finally, if incorporated into an interactive image processing system, this technique may be used as a planning tool allowing a surgical "rehearsal" prior to actual operative exposure and resection of a lesion.     

T2*-sensitized high-resolution magnetic resonance venography using 3D-PRESTO technique

PURPOSE: We evaluated the ability of the PRESTO (principles of echo shifting with a train of observations) technique to reveal small veins and microbleeds in the human brain. MATERIALS AND METHODS: In an experimental study, we calculated contrast-to-noise ratio (CNR) between a cerebral parenchymal phantom and human venous blood using 3 sequences of 3-dimensional (3D)-PRESTO, 3D-gradient recalled echo (GRE), and 3D-GRE echo-planar imaging (EPI). Then, we examined 7 healthy volunteers and 5 patients with venous angiomas or traumatic brain injuries using the 3D-PRESTO technique. In volunteer studies, MR venographies were reconstructed from 10-mm, 15-mm, and 20-mm thickness data using the minimum-intensity-projection (MinIP) technique. Three radiologists identified deep brain venous anatomy and counted the visible left medullary veins. In clinical studies, we evaluated the lesion conspicuity of small venous diseases and microbleeds. RESULTS: In the phantom study, 3D-PRESTO showed the highest CNR. In all volunteer studies, the deep brain venous anatomy was readily identified in the MinIP images at each thickness. The mean numbers of counted left medullary veins were 5.1 for 10 mm, 5.9 for 15 mm, and 6.7 for 20 mm in the MinIP images. The difference was significant between 10-mm and 20-mm MinIP images (P=0.02). In patient studies, abnormal small veins and microbleeds were clearly revealed. CONCLUSION: High-resolution MR venography using 3D-PRESTO technique can clearly depict small veins and microbleeds in the human brain.     

Pediatric head and neck lesions: assessment of vascularity by MR digital subtraction angiography

BACKGROUND AND PURPOSE: Pediatric head and neck lesions can be difficult to characterize on clinical grounds alone. We investigated the use of dynamic MR digital subtraction angiography as a noninvasive adjunct for the assessment of the vascularity of these abnormalities. METHODS: Twelve patients (age range, 2 days to 16 years) with known or suspected vascular abnormalities were studied. Routine MR imaging, time-of-flight MR angiography, and MR digital subtraction angiography were performed in all patients. The dynamic sequence was acquired in two planes at one frame per second by using a thick section (6-10 cm) selective radio-frequency spoiled fast gradient-echo sequence and an IV administered bolus of contrast material. The images were subtracted from a preliminary mask sequence and viewed as a video-inverted cine loop. RESULTS: In all cases, MR digital subtraction angiography was successfully performed. The technique showed the following: 1) slow flow lesions (two choroidal angiomas, eyelid hemangioma, and scalp venous malformation); 2) high flow lesions that were not always suspected by clinical examination alone (parotid hemangioma, scalp, occipital, and eyelid arteriovenous malformations plus a palatal teratoma); 3) a hypovascular tumor for which a biopsy could be safely performed (Burkitt lymphoma); and 4) a hypervascular tumor of the palate (cystic teratoma). CONCLUSION: Our early experience suggests that MR digital subtraction angiography can be reliably performed in children of all ages without complication. The technique provided a noninvasive assessment of the vascularity of each lesion that could not always have been predicted on the basis of clinical examination or routine MR imaging alone.     

Anatomic dissection tractography: a new method for precise MR localization of white matter tracts

BACKGROUND AND PURPOSE: Several white matter tracts in the brain cannot be identified on MR studies because they are indistinguishable from the surrounding white matter. We sought to develop a method to precisely localize white matter tracts by correlating anatomic dissections with corresponding MR images. METHODS: MR imaging was used to guide anatomic dissection of the uncinate fasciculus. Formalin-preserved brains were imaged before and after several stages of dissection. Progressive dissection was guided by using volume-rendered and cross-sectional images of the dissected specimens. To precisely define the location of a tract, its surface was traced on the corresponding three-dimensional MR image of the dissected specimen. MR images of the dissected and intact specimens were coregistered to allow the tracings to be projected onto multiplanar reformatted images of the intact specimen. RESULTS: The uncinate fasciculus in the anterior temporal lobe and external and extreme capsules was dissected without destroying adjacent structures. Coregistration of the MR images from intact and dissected specimens permitted precise MR identification of the surface of this tract. These methods were successful for two additional tracts. (The dissected anatomy, MR anatomy, and clinical examples of the three tracts are described in a companion article.) CONCLUSION: MR-assisted anatomic dissection permits limited removal of brain tissue so that important anatomic and surgical relationships can be demonstrated on correlated MR studies. This method can be applied to other white matter tracts that are indistinguishable on MR studies and to situations in which anatomic validation of normal and abnormal diffusion tractographic studies is needed.     

Brachytherapy for prostate cancer: endorectal MR imaging of local treatment-related changes

PURPOSE: To determine the local treatment-related endorectal magnetic resonance (MR) imaging findings after brachytherapy for prostate cancer. MATERIALS AND METHODS: Endorectal MR imaging was performed in 35 consecutive patients at a mean interval of 12 months (range, 1-31 months) after brachytherapy for prostate cancer. Transverse T1-weighted and high-spatial-resolution transverse and coronal T2-weighted images were acquired. Two readers reviewed MR image quality and findings, with discrepancies resolved by consensus. Posttreatment urinary symptoms in patients (n = 24) were documented by using chart review. RESULTS: All studies were of diagnostic quality. On T2-weighted images, prostatic findings consisted of diffuse low signal intensity (n = 35) and indistinct zonal anatomy (n = 34). Intra- and extraprostatic seed locations could be distinguished. The most common extraprostatic site of seed implantation was the neurovascular bundles (n = 35, bilateral in 32). The most common extraprostatic tissue finding was increased signal intensity on T2-weighted images in the levator ani muscle (n = 34) and the genitourinary diaphragm (n = 28). Postbrachytherapy urinary symptoms showed no demonstrable correlation with periurethral or genitourinary diaphragm seed implantation or with signal intensity change in the genitourinary diaphragm. CONCLUSION: Endorectal MR imaging can be used to evaluate seed distribution and to demonstrate treatment-related changes after brachytherapy for prostate cancer.