Contrast-enhanced Reformatted MR Images for Preoperative Assessment of the Bridging Veins of the Skull Base.

Magnetic resonance (MR) venography and computed tomographic (CT) venography are suited for displaying the convexity veins that drain the medial and lateral surfaces of the brain hemispheres. However, such is not the case for the bridging veins of the skull base. Technical factors prevent contrast material-enhanced MR or CT images obtained in standard axial, coronal, and sagittal planes from fully displaying the curved pathways of these clinically important venous structures. This limitation can be overcome by using a reconstruction technique that depicts these venous structures and their interconnections. Curved and multiplanar reformatted images that distill the important venous features often require knowledgeable manipulation of source images by an operator who is familiar with numerous venous variants and their surgical implications. The normal anatomy of the draining veins is detailed-anatomy that radiologists must master before they can show the surgeon the important venous anatomy that is often missing at standard imaging; this information will foster better communication between radiologists and their surgical colleagues. As a practical matter, the skull base veins are arbitrarily subdivided into those that are at greatest risk with the pterional approach and the subtemporal approach, respectively. These approaches can be expanded to define connections between the superficial venous system and the other valveless venous networks that drain the deep portions of the cerebral hemisphere, the scalp, face, muscles of the neck, diploë of the skull, and meninges. As radiologists gain experience, their image interpretations should mature beyond simple analysis of the primary hemodynamic changes induced by intraoperative sacrifice or injury.

Glial tumors in brodmann area 6: spread pattern and relationships to motor areas.

The posterior frontal lobe of the brain houses Brodmann area 4, which is the primary motor cortex, and Brodmann area 6, which consists of the supplementary motor area on the medial portion of the hemisphere and the premotor cortex on the lateral portion. In this area, safe resection is dependent on accurate localization of the motor cortex and the central sulcus, which can usually be achieved by using thin-section imaging and confirmed by using other techniques. The most reliable anatomic landmarks are the "hand knob" area and the marginal ramus of the cingulate sulcus. Postoperatively, motor deficits can occur not only because of injury to primary motor cortex but also because of injury to the supplementary motor area. Unlike motor cortex injury, the supplementary motor area syndrome is transient, if it occurs at all. On the lateral hemisphere, motor and language deficits can also occur because of premotor cortex injury, but a dense motor deficit would indicate subcortical injury to the corticospinal tract. The close relationship of the subcortical motor fibers and premotor cortex is illustrated. In contrast to the more constant landmarks of the central sulcus and marginal ramus, which aid in preoperative localization, the variable interruptions in the precentral and cingulate sulci of the posterior frontal lobe seem to provide "cortical bridges" for spread of infiltrating gliomas.

Deformable anatomic templates embed knowledge into patient's brain images: Part 1. Construction and display.

OBJECTIVE: This paper describes the methods used to create annotated deformable anatomic templates (DATs) and display them in a patient's axial 2-dimensional and reformatted volume brain images. METHODS: A senior neuroradiologist annotated and manually segmented 1185 color-coded structures on axial magnetic resonance images of a normal template brain using domain knowledge from multiple medical specialties. Besides the visible structures, detailed pathways for vision, speech, cognition, and movement were charted. This was done by systematically joining visible anatomic anchor points and selecting the best fit based on comparisons with cadaver dissections and the constraints defined on the companion 2-dimensional images. RESULTS: The DAT is commercially available for use on a picture archiving and communication system or as a standalone workstation. CONCLUSIONS: The DAT can quickly embed extensive, clinically useful functional neuroanatomic knowledge into the patient's brain images. Besides labeling visible structures, DAT displays clinically important, previously uncharted subdivisions of the fiber tracts.

Deformable anatomic templates embed knowledge into brain images: part 2. Validation using functional magnetic resonance imaging of the motor hand.

OBJECTIVE: This study evaluated the concordance between the Deformable Anatomic Template (DAT)-identified origin of motor hand fibers and localization of the motor cortex of the hand by functional magnetic resonance imaging (fMRI). METHODS: Preoperative fMRI during hand motor tasks was performed on 36 hemispheres in 26 patients with gliomas in or near eloquent areas. Reformatted volume-rendered surface images were labeled with the DAT's hand motor fibers and fMRI data. Five reviewers assessed the data for concordance. RESULTS: Available fMRI data were diagnostically usable in 92% (33/36 analyzed hemispheres), with DAT anatomic accuracy in the remaining cases. The DAT prediction and fMRI findings were concordant in all 9 normal hemispheres and in 20 (83%) of 24 glioma-bearing hemispheres. The 4 discordant cases resulted from substantial mass effect by large frontal tumors. CONCLUSIONS: This study validated DAT's anatomic atlas and alignment process for the expected position of the motor cortex of the hand.

Arterial anatomy of the pancreas. Part 3: segmented computed tomography-angiography mapping of perineural invasion.

This is the third in a series of medical graphics articles featuring the arterial anatomy of the pancreas as depicted on segmented computed tomography-angiography. These segmented computed tomography-angiography displays serve as a road map of the routes of tumor spread by ductal adenocarcinoma of the pancreas because perineural tumor invasion parallels the pancreatic arteries.

Arterial anatomy of the pancreas: part 2. Axial.

This is the second in a 3-part series of medical graphics articles featuring the arterial anatomy of the pancreas as depicted on computed tomography images. Tumor encasement of the peripancreatic arteries is a hallmark of ductal adenocarcinoma.

Arterial anatomy of the pancreas: part 1. Coronal.

This is the first in a series of 3 medical graphics articles featuring the arterial anatomy of the pancreas as depicted on computed tomography images. This arterial anatomy is important in clinical practice because it represents a road map of the routes of tumor spread by ductal adenocarcinoma of the pancreas.

MRI venous architecture of the thalamus.

PURPOSE: Our purpose is to describe the thalamic veins using a novel approach named venous gliography in cases with primary or secondary gliomas of the thalamus. Venous gliography is defined by authors as a method to visualize veins on MRI Brain T1-weighted post contrast scans containing gliomas which have induced regional venous congestion. METHODS: Routine clinical MR Imaging studies were reviewed to assess the presence of thalamic veins in 29 glioma cases. In addition, confocal reconstruction techniques (Anatom-e and Osirix) were used in cases that had thin sections (1.0-1.5mm) post contrast T1 weighted sequences. Multiplanar MIP and confocal volume rendered images were generated to evaluate the thalamic veins in those cases. RESULTS: Using venous gliography and confocal reconstruction techniques, two patterns in the venous architecture of the thalamus were documented. First, the branching pattern created by the tributaries of the internal cerebral vein, namely the superior thalamic vein and the anterior thalamic vein, which together formed the superior group of thalamic veins. Second, the pattern created by the un-branched vertically oriented veins, namely the inferior thalamic veins and the posterior thalamic veins, which joined the basal vein of Rosenthal and constituted the inferior group of thalamic veins. CONCLUSIONS: Venous gliography combined with the use of confocal reconstruction techniques provided a novel approach to display the thalamic veins that are usually not seen. The understanding of the venous architecture is mandated by the recent research where veins have taken on an important role in the perivenular spread of gliomas.

The evaluation of isolated third nerve palsy revisited: an update on the evolving role of magnetic resonance, computed tomography, and catheter angiography.

The evaluation and management of the neurologically isolated third nerve palsy continues to evolve. The major concern for the clinician confronted with a patient with a third nerve palsy has been the exclusion of an intracranial aneurysm. The evolution of new imaging techniques, such as computed tomography angiography and magnetic resonance angiography, have provided new imaging options for clinicians. This article reviews the pertinent recent literature on the use of these imaging studies in evaluating the patient with a third nerve palsy.

Patterns of lymphadenopathy in thoracic malignancies.

There are different lymphatic drainage pathways in the thorax that are relevant in the staging of lung cancer, breast cancer, lymphoma, esophageal cancer, and malignant mesothelioma. To properly search for metastatic spread, it is important to carefully evaluate the specific nodal stations that drain the thoracic structures from which a primary tumor originates. Because size criteria have limitations in the prediction of nodal status, pathologic confirmation is essential for accurate staging. Computed tomography (CT) is useful in helping the surgeon or interventional radiologist determine the most appropriate approach for nodal sampling. Fluorine-18 fluorodeoxyglucose (FDG) positron emission tomography (PET) has an increasing role in detection of diseased lymph nodes that appear normal at CT alone, particularly when FDG PET images are fused with CT images. However, the role of radiologic imaging extends beyond initial staging and the guidance of interventions to include posttreatment assessment and the detection of recurrent disease. Therefore, at all levels of cancer imaging, it is essential to identify the relevant lymph node regions and their relations to the primary tumor.

Deformable anatomic templates improve analysis of gliomas with minimal mass effect in eloquent areas.

BACKGROUND: Despite improvements in advanced magnetic resonance imaging and intraoperative mapping, cases remain in which it is difficult to determine whether viable eloquent structures are involved by a glioma. A novel software program, deformable anatomic templates (DAT), rapidly embeds the normal location of eloquent cortex and functional tracts in the magnetic resonance images of glioma-bearing brain. OBJECTIVE: To investigate the feasibility of the DAT technique in patients with gliomas related to eloquent brain. METHODS: Forty cases of gliomas (grade II-IV) with minimal mass effect were referred for a prospective preoperative and postoperative DAT analysis. The DAT results were compared with the patient's functional magnetic resonance imaging, diffusion tensor imaging, operative stimulation, and new postoperative clinical deficits. RESULTS: Fifteen of the 40 glioma patients had overlap between tumor and eloquent structures. Immediate postoperative neurological deficits were seen in 9 cases in which the DAT showed the eloquent area both within the tumor and within or at the edge of the resection cavity. In 6 cases with no deficits, DAT placed the eloquent area in the tumor but outside the resection cavity. CONCLUSION: This is proof of concept that DAT can improve the analysis of diffuse gliomas of any grade by efficiently alerting the surgeon to the possibility of eloquent area invasion. The technique is especially helpful in diffuse glioma because these tumors tend to infiltrate rather than displace eloquent structures. DAT is limited by tract displacement in gliomas that produces moderate to severe mass effect.

High-resolution computed tomography of temporal bone: Part IV: Coronal postoperative anatomy.

The purpose of this 4-part series is to illustrate the nuances of temporal bone anatomy using a high-resolution (200 micro isotropic) prototype volume computed tomography (CT) scanner. The normal anatomy in axial and coronal sections is depicted in the first and second parts. In this, the fourth part, and the third part, the structures that are removed and/or altered in 9 different surgical procedures are color coded and inscribed in the same coronal (article IV) and axial (article III) sections. The text stresses clinically important imaging features, including the normal postoperative appearance, and common complications after these operations. The superior resolution of the volume CT images is vital to the comprehensive and accurate representation of these operations. Minuscule intricate structures that are currently only localized in the mind's eye because of the resolution limit of conventional CT are clearly seen on these scans. This enhanced visualization, together with the information presented in the text, should assist in interpreting temporal bone scans, communicating with surgeons, and teaching this complex anatomy.

High-resolution computed tomography of temporal bone: Part III: Axial postoperative anatomy.

The purpose of this 4-part series is to illustrate the nuances of temporal bone anatomy using a high-resolution (200-mu isotropic) prototype volume computed tomography (CT) scanner. The normal anatomy in axial and coronal sections is depicted in the first and second parts. In this and the subsequent part, the structures that are removed and/or altered in 9 different surgical procedures are color coded and inscribed in the same axial (article III) and coronal (article IV) sections. The text stresses clinically important imaging features, including the normal postoperative appearance, and common complications after these operations. The superior resolution of the volume CT images is vital to the comprehensive and accurate representation of these operations. Minuscule intricate structures that are currently only localized in the mind's eye because of the resolution limit of conventional CT are clearly seen on these scans. This enhanced visualization, together with the information presented in the text, should assist in interpreting temporal bone scans, communicating with surgeons, and teaching this complex anatomy.

Adult cranial dura II: venous sinuses and their extrameningeal contributions.

This is the second of two articles designed to provide detailed user-friendly schematics of the adult dural vascular anatomy. It supplements the first article on the intrinsic meningeal arteries and veins by describing the dural venous sinuses along with their three remaining connections: to the brain, to the diploë, and to the extracranial soft tissues. The discussion of this anatomy is supplemented by illustrative pathologic insights. This information will assist in interpreting neuroimaging studies, communication with clinicians, and teaching of this complex subject.

A computed tomographic guide to endoscopic sinus surgery: axial and coronal views.

SUMMARY: The purpose of this article is to correlate endoscopic surgical procedures in the sinuses with computer tomographic (CT) scans. Twelve commonly performed procedures were color-coded on a set of normal coronal and axial CT scans. The illustrated procedures are uncinectomy/antrostomy, anterior ethmoidectomy, posterior ethmoidectomy, sphenoidotomy, partial inferior turbinectomy, partial middle turbinectomy, septoplasty, frontal recess approach, dacrocystorhinostomy, orbital decompression, optic nerve decompression, and medial maxillectomy. Drainage of a medial orbital abscess is discussed but not illustrated. A brief description of the indications, surgical approach, and complications of each procedure is also provided.

Intracranial auditory pathways: anatomy correlated with evoked response data.

The intracranial auditory pathways are complex, and they have been incompletely mapped. The purpose of the communication is to summarize what is known about these fibers onto clinically relevant imaging sections. Anatomic information is correlated with the clinical auditory evoked responses currently used to localize lesions in these pathways. This linkage will improve communication between imagers and clinicians. In addition, it can be used for teaching.

Coronal imaging of the osteomeatal unit: anatomy of 24 variants.

The purpose of this paper is to present a user-friendly reference for 24 of the most common normal variants of the osteomeatal unit. A five image set of consecutive normal coronal hanging head computed tomography (CT) images was obtained. Half of each image was duplicated enough times to allow superimposition of the variants. For organizational purposes, each variant was sorted into six color-coded regions: middle turbinate (five variants), inferior turbinate (three variants), maxillary sinus (three variants), nasal septum (three variants), ethmoid sinuses (five variants), and uncinate process (five variants). This reference can be used to rapidly identify a CT scan level and obtain an overview of common variants in that level. In addition, the color-coded system can be used to find any variant on all appropriate CT levels quickly by locating its colored column.

A functional imaging guide to the bony landmarks of the seventh nerve.

This article links the imaging anatomy of the skull base with the seventh cranial nerve's pathway. The specific landmarks are illustrated, and the clinical presentations of lesions are defined. Unifying the anatomic and clinical features of the seventh nerve will improve detection of small lesions, assist in communication between clinicians, and aid in teaching this complex subject.