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Biomedical subjects

Thomas P Naidich

Publications and source records attributed to Thomas P Naidich.

At least 19 recordsLinked to original sources
PubMed2006

Role of 3D CT in the evaluation of the temporal bone.

In recent years, three-dimensional (3D) multiplanar reformatted images from conventional cross-sectional computed tomographic (CT) data have been increasingly used to better demonstrate the anatomy and pathologic conditions of various organ systems. Three-dimensional volume-rendered (VR) CT images can aid in understanding the temporal bone, a region of complex anatomy containing multiple small structures within a relatively compact area, which makes evaluation of this region difficult. These images can be rotated in space and dissected in any plane, allowing assessment of the morphologic features of individual structures, including the small ossicles of the middle ear and the intricate components of the inner ear. The use of submillimeter two-dimensional reconstruction from CT data in addition to 3D reformation allows depiction of microanatomic structures such as the osseous spiral lamina and hamulus. Furthermore, 3D VR CT images can be used to evaluate various conditions of the temporal bone, including congenital malformations, vascular anomalies, inflammatory or neoplastic conditions, and trauma. The additional information provided by 3D reformatted images allows a better understanding of temporal bone anatomy and improves the ability to evaluate related disease, thereby helping to optimize surgical planning.

Bone Diseases↗
PubMed2005

MRI findings in an atypical case of Kearns-Sayre syndrome: a case report.

MR imaging features of mitochondrial encephalomyopathies, lactic acidosis, and stroke-like episodes, Kearns-Sayre/Pearson syndrome have been described in the literature. We describe extensive white matter changes with abnormal signal intensity lesions involving the deep gray nuclei and myelinated white matter tracts in an 18-year-old female with a large-scale 7.4 kb mitochondrial DNA deletion and a atypical presentation of Kearns-Sayre syndrome. Restricted diffusion due to status spongiosus at the involved sites is also discussed.

Adolescent↗
PubMed2005

Brainstem vascular stroke anatomy.

Brainstem infarcts comprise approximately 10% of all first ischemic brain strokes. The extrinsic vascular supply to the stem is complex. The intrinsic vascularization of the stem may be conceptualized in terms of four relatively constant and distinct vascular territories designated anteromedial, anterolateral, lateral, and dorsal (or dorsolateral). The anatomic structures found within each intrinsic territory determine the symptomatology associated with infarction of that territory. This territorial anatomy permits the knowledgeable physician to plan an MR imaging examination tailored to the patient's history and to predict the patient's neurologic deficits from the MR imaging findings.

Brain Stem↗
PubMed2005

Trigeminal ganglion and its divisions: detailed anatomic MR imaging with contrast-enhanced 3D constructive interference in the steady state sequences.

BACKGROUND AND PURPOSE: Visualization of the trigeminal system is important for imaging diagnosis but technically challenging. We assessed how well the trigeminal ganglion, its rootlets, and its branches (V1, V2, and V3) are depicted on three high-resolution pulse sequences. METHODS: Twenty-two patients (44 sides) underwent nonenhanced 3D constructive interference in the steady state (CISS) MR imaging. Two of these patients and another 20 (44 sides) also underwent contrast-enhanced 3D CISS and contrast-enhanced 3D time-of-flight (TOF) MR angiographic (MRA) imaging. Appearances of the ganglion, sinus ganglii, ganglion lip, and sensory and motor rootlets in the Meckel cave were assessed. RESULTS: The trigeminal ganglion was shown on enhanced 3D CISS images in all cases, on nonenhanced 3D CISS images in 77.3%, and on enhanced 3D TOF MRA images in 92.9%. Sinus ganglia and lips were demonstrated on 98% of enhanced 3D CISS images. Sensory rootlets were depicted with all 3D CISS sequences but no 3D TOF sequences. V1, V2, and V3 were displayed with all enhanced 3D TOF MRA sequences, 79.5-100% of enhanced 3D CISS sequences, and 0-50% of nonenhanced 3D CISS sequences. CONCLUSION: The enhanced 3D CISS sequence was best for displaying the trigeminal ganglion, sinus ganglii, and sinus lips, whereas the enhanced 3D TOF sequence best displayed the emerging V1, V2, and V3 roots. The enhanced 3D CISS sequence was most useful. Complete MR imaging evaluation of the trigeminal ganglion and roots is best performed by using enhanced 3D CISS and enhanced 3D TOF MRA sequences.

Adult↗
PubMed2004

Exophytic pilocytic astrocytoma of the brain stem in an adult with encasement of the caudal cranial nerve complex (IX-XII): presurgical anatomical neuroimaging using MRI.

We describe a rare case of adult pilocytic astrocytoma in which exophytic growth from the brain stem presented as a right cerebellopontine angle mass. An initial MRI examination using T2- and T1-weighted images without and with contrast suggested the diagnosis of schwannoma. Subsequent use of 3D CISS (three-dimensional constructive interference in steady state) and T1-weighted contrast-enhanced 3D MP-RAGE (three-dimensional magnetization prepared rapid acquisition gradient echo) sequences led to the diagnosis of an exophytic brain stem tumor, documented the precise relationships of the tumor to cranial nerve VIII, revealed encasement of cranial nerves IX-XII (later confirmed intraoperatively), and provided the proper basis for planning surgical management.

Accessory Nerve↗
PubMed2004

Acute intermittent porphyria: studies of the severe homozygous dominant disease provides insights into the neurologic attacks in acute porphyrias.

BACKGROUND: Acute intermittent porphyria (AIP), due to half-normal hydroxymethylbilane synthase activity,is characterized by acute life-threatening neurologic attacks whose etiology remains unclear. To date, only 3 patients confirmed to have homozygous dominant AIP (HD-AIP) have been described (hydroxymethylbilane synthase genotypes R167Q/R167Q and R167W/R173Q). OBJECTIVE: To investigate the genetic, biochemical, clinical, and neuroradiologic features of a severely affected infant with HD-AIP. DESIGN: Clinical, imaging, and genotype/phenotype studies were performed. RESULTS: The proband, homoallelic for hydroxymethylbilane synthase mutation R167W, had approximately 1% of normal hydroxymethylbilane synthase activity, elevated porphyrins and porphyrin precursors, severe psychomotor delay, and central and peripheral neurologic manifestations. When expressed in vitro, the R167W mutant enzyme had less than 2% of normal activity but was markedly unstable, consistent with the proband's severe phenotype. Mitochondrial respiratory chain enzymes were normal. Neuroradiologic studies revealed a unique pattern of deep cerebral white matter injury, with relative preservation of the corpus callosum, anterior limb of the internal capsule, cerebral gray matter, and infratentorial structures. CONCLUSIONS: This severely affected patient with HD-AIP expanded the phenotypic spectrum of HD-AIP. His brain magnetic resonance imaging studies suggested selective cerebral oligodendrocyte postnatal involvement in HD-AIP, whereas most structures developed prenatally were intact. These findings indicate that the neurologic manifestations result from porphyrin precursor toxicity rather than heme deficiency and suggest that porphyrin precursor toxicity is primarily responsible for the acute neurologic attacks in heterozygous AIP and other porphyrias.

Acute Disease↗
PubMed2004

Brain structure variation in great apes, with attention to the mountain gorilla (Gorilla beringei beringei).

This report presents data regarding the brain structure of mountain gorillas (Gorilla beringei beringei) in comparison with other great apes. Magnetic resonance (MR) images of three mountain gorilla brains were obtained with a 3T scanner, and the volume of major neuroanatomical structures (neocortical gray matter, hippocampus, thalamus, striatum, and cerebellum) was measured. These data were included with our existing database that includes 23 chimpanzees, three western lowland gorillas, and six orangutans. We defined a multidimensional space by calculating the principal components (PCs) from the correlation matrix of brain structure fractions in the well-represented sample of chimpanzees. We then plotted data from all of the taxa in this space to examine phyletic variation in neural organization. Most of the variance in mountain gorillas, as well as other great apes, was contained within the chimpanzee range along the first two PCs, which accounted for 61.73% of the total variance. Thus, the majority of interspecific variation in brain structure observed among these ape taxa was no greater than the within-species variation seen in chimpanzees. The loadings on PCs indicated that the brain structure of great apes differs among taxa mostly in the relative sizes of the striatum, cerebellum, and hippocampus. These findings suggest possible functional differences among taxa in terms of neural adaptations for ecological and locomotor capacities. Importantly, these results fill a critical gap in current knowledge regarding great ape neuroanatomical diversity.

Animals↗
PubMed2004

Neuroanatomy of the killer whale (Orcinus orca) from magnetic resonance images.

This article presents the first series of MRI-based anatomically labeled sectioned images of the brain of the killer whale (Orcinus orca). Magnetic resonance images of the brain of an adult killer whale were acquired in the coronal and axial planes. The gross morphology of the killer whale brain is comparable in some respects to that of other odontocete brains, including the unusual spatial arrangement of midbrain structures. There are also intriguing differences. Cerebral hemispheres appear extremely convoluted and, in contrast to smaller cetacean species, the killer whale brain possesses an exceptional degree of cortical elaboration in the insular cortex, temporal operculum, and the cortical limbic lobe. The functional and evolutionary implications of these features are discussed.

Animals↗
PubMed2004

The carpal tunnel: ultrasound display of normal imaging anatomy and pathology.

Ultrasound successfully displays the normal anatomy and pathology of the median nerve in the carpal tunnel. This article reviews the sonographic characteristics of carpal tunnel anatomy, including the superficially situated median nerve, the contained tendons and vessels, and the boundary-forming fibro-osseous landmarks. It emphasizes ultrasound evaluation of the median nerve and the criteria for diagnosis of compressive neuropathy in carpal tunnel syndrome. The techniques for performing sonography for carpal tunnel syndrome are detailed. Ultrasonic imaging is more comfortable for patients, less time-consuming, and less expensive than MR imaging, and achieves equal accuracy in skilled hands.

Bone Diseases↗
PubMed2004

Embryogenesis of the peripheral nervous system.

Embryogenesis is a complex, wide-ranging event. Key processes may proceed simultaneously in different portions of the embryo, or sequentially, with phase offsets as waves of maturation pass outward from an initial point toward the periphery. The molecular signals used to pattern the body commonly serve multiple functions and reiterate as the body plan progresses. This article therefore presents first the anatomic model of the peripheral nervous system, so that the final goal is clear. It then reviews the terminology needed to describe embryogenesis. The article's first section reviews neural development. The main portion of the article addresses the maturation of the fetal nervous system in terms of the evolving gross morphology and the molecular signals that pattern these changes.

Embryonic and Fetal Development↗
PubMed2004

The rare phakomatoses.

This article outlines the clinical, central nervous system, and neuropathologic features,pathogenesis, genetics, molecular biology, and neuroimaging characteristics of the rare vascular phakomatoses, melanophakomatoses, and organoid phakomatoses.

Brain↗
PubMed2004

Detailed anatomy of the motor and sensory roots of the trigeminal nerve and their neurovascular relationships: a magnetic resonance imaging study.

OBJECT: The trigeminal nerve conducts both sensory and motor impulses. Separate superior and inferior motor roots typically emerge from the pons just anterosuperomedial to the entry point of the sensory root, but to date these two motor roots have not been adequately displayed on magnetic resonance (MR) images. The specific aims of this study, therefore, were to identify the superior and inferior motor roots, to describe their exact relationship to the sensory root, and to assess the neurovascular relationships among all three roots of the trigeminal nerve. METHODS: Thirty-three patients and seven cadaveric specimens (80 sides) were studied using three-dimensional (3D) Fourier transform constructive interference in steady-state (CISS) imaging. The 33 patients were also studied by obtaining complementary time-of-flight (TOF) MR angiography sequences with and without contrast enhancement. At least one motor root was identified in all sides examined: in 51.2% of the sides a single motor root, in 37.5% two motor roots, and in 11.2% three motor roots. The superior cerebellar artery (SCA) and the anterior inferior cerebellar artery (AICA) contacted the sensory root in 45.5% of patients and 42.9% of specimens. The SCA often contacted the superior motor root (48.5% of patients and 50% of specimens) and less frequently the inferior motor root (26.5% of patients and 20% of specimens). CONCLUSIONS: Three-dimensional CISS and complementary 3D TOF MR angiography sequences reliably display sensory, superior motor, and inferior motor roots of the trigeminal nerve and their relationships to the SCA and AICA.

Adult↗
PubMed2004

Surgery for Rathke cleft cysts: technical considerations and outcomes.

OBJECT: The aim of this study was to identify the optimal surgical goals and techniques for managing symptomatic Rathke cleft cysts (RCCs). METHODS: The authors conducted a retrospective study of 62 consecutive patients who had undergone surgery for RCCs. Postoperative follow up was a mean of 28 months. Fifty-six patients underwent transsphenoidal cyst decompression and biopsy procedures, and six underwent cyst wall resection. Postoperatively, symptoms improved in 91% of patients with headaches and 92% of patients with visual deficits. Decompression and biopsy were associated with a 10% incidence of new anterior pituitary hormone deficiencies and a 6% incidence of new permanent diabetes insipidus; the incidence of new hormone deficiencies was significantly higher in the few patients who had undergone cyst wall resection. The incidence of relapse, defined as cyst regrowth with either recurrent symptoms or chiasmal compression, was 16%. Resection of the cyst wall was associated with a trend toward a decreased risk of relapse. Sellar packing, sellar floor reconstruction, and irrigation with absolute ethanol did not affect the likelihood of relapse. Squamous metaplasia and inflammation increased the risk of relapse. Residual cyst demonstrated on postoperative magnetic resonance imaging was associated with an increased risk of subsequent asymptomatic cyst regrowth. Seven patients (11%) underwent repeated operation with symptomatic improvement and minimal morbidity; only one patient relapsed following a second surgery. CONCLUSIONS: Decompression and biopsy procedures in the treatment of RCCs lead to improvement in signs and symptoms, with low morbidity rates. Repeated operations will be required in as many as 16% of patients but are also associated with symptomatic improvement, low morbidity, and durable remission. Decompression and biopsy may represent the optimal surgical management of RCC.

Adolescent↗
PubMed2004

The insula: anatomic study and MR imaging display at 1.5 T.

BACKGROUND AND PURPOSE: The insula is important for gustatory sensation, motor speech control, vestibular function, and sympathetic control of cardiovascular tone. The purpose of this study was to test two hypotheses: 1) gross anatomic study of the insula will disclose reproducible patterns of insular structure, and 2) analysis of MR appearance will enable physicians to recognize these patterns on imaging studies. METHODS: Gross insular anatomy was determined in 16 normal human cadaveric hemispheres. The 1.5-T MR images of 300 insulae were analyzed to determine the gyral and sulcal patterns displayed; their relationship to the Heschl gyrus, to the overlying opercula, and to the vertical planes perpendicular to the Talairach-Tournoux baseline at the anterior commissure (VAC) and posterior commissure (VPC); their continuity into the orbitofrontal cortex; and appropriate landmarks for the anterior border, apex, and posterior border of the insula. RESULTS: MR images displayed the central sulcus of the insula (97%); the anterior (99%), middle (78%), and posterior (98%) short insular gyri that converge to the apex (100%) anteriorly; and the anterior (99%) and posterior (58%) long insular gyri posteriorly. The middle short gyrus was often hypoplastic (33%). The anterior intersections of the internal and external capsules typically delimit the anterior insular border (87%). VAC intersects the anterior insula (99%), usually at the precentral sulcus. The Heschl gyrus circumscribes the posteroinferior insula (100%). VPC demarcates the posterior insular border (94%). CONCLUSION: The two hypotheses were proved correct. The insula shows reproducible patterns of gross anatomy that are demonstrable on routine clinical MR images obtained at 1.5 T.

Adolescent↗
PubMed2003

Zonal frequency analysis of infarct extent. Part II: anterior and posterior cerebral artery infarctions.

The object of the study was to test the hypotheses that analysis of the anatomic zones affected by single anterior (A), posterior (P), and middle (M) cerebral artery (CA) infarcts, and by dual- and triple-vessel infarcts, will disclose (i) sites most frequently involved by each infarct type (peak sites), (ii) sites most frequently injured by multiple different infarct types (vulnerable zones), and (iii) anatomically overlapping sites in which the relative infarct frequency becomes equal for two or more different infarct types and/or in which infarct frequency shifts greatly between single and multivessel infarcts (potential border zones). Precise definitions of each vascular territory were adopted. CT and MRI studies from 20 ACA, 20 PCA, three dual ACA-PCA, and four triple ACA-PCA-MCA infarcts were mapped onto a standard template (Part I). Relative infarct frequencies in each zone were analyzed within and across infarct types to identify the centers and peripheries of each infarct type, the zones most frequently affected by multiple different infarct types, the zones where relative infarct frequency was equal for different infarcts, and the zones where infarct frequency shifted markedly from single- to multiple-vessel infarcts. Zonal frequency analysis provided quantitative data on the relative infarct frequency in each anatomic zone for each infarct type. It displayed zones of peak infarct frequency for each infarct, zones more vulnerable to diverse types of infarct, peripheral "overlap" zones of equal infarct frequency, and zones where infarct frequency shifted markedly between single- and multiple-vessel infarcts. It is concluded that the hypotheses are correct.

Adolescent↗
PubMed2003

MR microscopy of normal human brain.

MR microscopy at 9.4T depicts the architecture of the brain in exquisite detail, including the individual laminae of the cortex, the individual nuclei of the basal ganglia, the thalami, subthalami and metathalami, and the orientations and relationship among the dominant nuclei and white matter tracts of the brain. The authors believe that these anatomic relations will ultimately be displayed in vivo as clinical MR scanners begin to operate at field strengths of 4.7T, 7T, and 8T. Then, those familiar with this anatomy will be able to interpret patient images with far greater sophistication.

Basal Ganglia↗
PubMed2003

Assessment of the patient with hyperacute stroke: imaging and therapy.

Neuroimaging is an important part of the assessment of patients with hyperacute stroke. As new treatments that may reverse cerebral ischemia have been developed, the role of neuroimaging has changed from simply anatomic depiction of early infarction to identification, by means of physiologic (rather than simply anatomic) information, of regions that are at risk for infarction. The goal of such imaging techniques is to monitor successes and complications of recently developed treatments such as thrombolysis.

Acute Disease↗